Cities as Platforms for Population Health: Past, Present, and Future

Most of the world's population lives in cities. more than 56% of people lived in urban areas in 2020, while only 29% did in 1950. This proportion is significantly higher in Europe and North America, where 75% and 84% of the population, respectively, is urban. ¹ By 2050, nearly 70% of people globally will live in cities. ²

The health of urban populations is dramatically influenced by the urban context, including its social, economic, environmental, and political conditions, in both positive and negative ways. ³ , ⁴ Socially, the geographic concentration and colocation of people facilitate the formation of health‐promoting social networks, while poor sanitation and high crime rates in population‐dense areas feed the spread of communicable disease and physical injury. Economically, cities produce 80% of global gross domestic product, offering attractive employment prospects and elevating living standards but distributing both opportunities and gains from production unevenly, which drives urban poverty and growing inequality. Environmentally, robust transportation makes the workplaces and amenities of cities more accessible but contributes to air and noise pollution and rising carbon emissions, exacerbating associated health risks and climate change. Politically, opportunities for participatory democracy and community‐level self‐determination are often constrained by systematic disenfranchisement of marginalized populations and municipal corruption. The interplay of these complex factors occurs in the background of evolving challenges in health and medicine, ranging from aging populations and growing health care expenditures to novel pathogens and global pandemics.

It is widely accepted that population health is a function of both upstream (e.g., economic circumstances, physical environment) and downstream (e.g., access to high‐quality medical care) factors. ⁵ Urbanization—the population shift from rural to urban areas—has uniquely shaped each of these inputs and the interactions among them, frequently producing a net “urban health penalty” for many people who live in cities. ⁶ , ⁷ Why and exactly how cities impact health has been the subject of significant scholarship. ⁸ Galea and colleagues (2004) introduced a framework for urban health in which health outcomes are the product of the social and physical environments of urban life that are shaped by municipal factors and the national and global trends that affect how local factors operate. ⁹ These municipal‐level determinants include activities of governments, markets, and civil society that influence the health of urban populations.

In the wake of COVID‐19, we have a once‐in‐a‐generation opportunity to reevaluate these factors and reimagine their role in urban health. Evidently, cities can have both positive and negative effects on health. A critical question for city leaders, then, is, how do we use municipal policies to mitigate and, where possible, address the root causes of the deleterious impact of urbanization on health while preserving and promoting the health‐enhancing aspects of cities? In this Perspective, we review a brief history of municipal health policies, identify key challenges for cities, discuss promising strategies to advance population health in urban centers, and offer a vision for the future of urban health.

Cities as the Birthplace of Public Health

The rise of cities played a central role in the origin of public health. ¹⁰ In the 17^th century, as the transmissible nature of communicable diseases became clear, cities around the world, especially port cities, adopted rules for quarantine and isolation of the sick. By the start of the 18^th century, several European cities appointed public authorities to enforce these measures in response to repeated epidemics of plague, smallpox, and other contagions. Soon after, multiple US cities, including Boston, Philadelphia, New York, and Baltimore, convened permanent councils to adopt and enforce such rules. ¹¹ These efforts coincided with the large‐scale migration of people into cities driven by industrialization.

Growing population density in urban centers, overcrowded housing, and inadequate shared systems of water and sewage created a nidus for infectious disease, contributing to vigorous debate over germ theory and prompting pioneering work in public health, including John Snow's classic study of cholera in London. ¹² Rapid urbanization often outpaced the development of basic infrastructure, including waste management, creating unsanitary living conditions and breeding grounds for diseases such as tuberculosis, typhus, and smallpox, severely limiting life expectancy of working‐class urban populations. ¹³ In his famous General Report on the Sanitary Conditions of the Labouring Population of Great Britain, Edwin Chadwick documented the inferior living conditions among the poor, relating those conditions to drastically worse health outcomes: laborers reportedly lived 20 fewer years on average than the gentry. ¹⁴ His findings exposed the human costs of economic development achieved through industrialization—costs that fell disproportionately on the urban poor—while highlighting the need for public intervention. He proposed local boards of health and district medical officers to oversee new drainage networks and other measures. Chadwick's report heavily shaped the Public Health Act of 1848, a seminal piece of legislation with a lasting influence on public health, in England and around the world. ¹⁵

Chadwick's report also kindled similar efforts in the United States, including Lemuel Shattuck's 1850 Report of the Massachusetts Sanitary Commission. ¹⁶ Shattuck described the sanitary movement, linked disparities in morbidity and mortality to urban living conditions, and made several recommendations, including routine surveys of local health conditions, supervision of water and waste disposal, and local health boards to enforce sanitary regulations. ¹⁷ Many of these principles guide American public health practice to this day. Around the same time, a similar report was released in New York, ¹⁸ leading to the establishment of the first public agency for health, the New York City Health Department, in 1866. The initial activities of these early agencies were limited to sanitation, inspection, disinfection, and case reporting.

As public health matured over the late nineteenth century, local health departments proliferated, as did their resources, responsibilities, and capabilities to combat communicable disease. As bacteriology advanced, municipal health agencies built laboratories to detect pathogens in water and food. Mandated reporting and registries to track the spread of disease became commonplace, in concert with immunization and education to control spread. The early 20th century saw these departments increasingly take on the responsibility of providing personal care. They began to diagnose disease in individuals and treat them with antitoxins and other early remedies. City health departments opened and operated hundreds of tuberculosis clinics, and some even offered home visits by public health nurses (New York, Baltimore). Other clinics focused on infant mortality.

The mid‐20th century saw further expansion of governmental involvement in public health. Federal legislation led to increased funding and technical assistance to local health departments to provide services related to maternal and child health, family planning, immunization, and infectious disease control. Simultaneously, the creation of the Medicare and Medicaid programs led to many funds bypassing local governments and going directly to private health care providers, fostering a division between public health and health care that continued through the late 20th century. While the provision of clinical care was de‐emphasized, the scope of public health agencies expanded in other ways as they tackled upstream risk factors, including tobacco use and vehicular safety. ¹⁹

Public health was born in cities. The urban context laid bare the relationship that sits at the core of public health: the conditions in which people live and work are key determinants of their health and well‐being. In so doing, it also gave rise to the first municipal policies—targeted primarily at controlling the spread of infectious diseases—and established the role of government in protecting the health of city inhabitants, especially the least well off.

Municipal Responses to Epidemiologic Transition

As public health agencies became more effective in combating infectious disease and societies modernized, the burden of disease shifted in much of the Western world. Whereas communicable disease had been the traditional driver of mortality and morbidity, noncommunicable diseases gradually replaced contagion as the primary determinant of population health in the United States, following the well‐described “epidemiological transition” documented in England. ²⁰ , ²¹ As life expectancy rose, the relative importance of different causes of death changed. While noncommunicable diseases accounted for less than 20% of deaths in the US in 1900, they accounted for almost 80% in 2000. ²² Broadly speaking, the burden had shifted from acute to chronic and from pathogen‐mediated (e.g., tuberculosis) to lifestyle‐mediated (e.g., high blood pressure). Tobacco use, unhealthy diet, lack of physical activity, and alcohol use gradually replaced poor sanitation and inadequate sewage as the major risk factors for preventable disease. This transition coincided with the gradual evolution of epidemiology from the study of individual risk factors to a broader “social epidemiology” that sought to understand these risk factors in a broader socioeconomic context. ²³ , ²⁴

This turning point posed a dilemma for public health agencies, charged with the broad responsibility to protect the health of populations but more narrowly designed and resourced to control the spread of infectious disease. ²⁵ The key risk factors for noncommunicable diseases reflect human behaviors, but because people's behavior is profoundly shaped by their physical and social environment, population‐level impact can best be achieved through policy changes designed to make healthy choices easier. ²⁶ Local health departments were slow to respond to this shift in responsibility. In fact, health departments were described by one expert as being “asleep at the switch” with respect to the rise of chronic disease, due to funding inadequacies, entrenchment in historical roles, and the lack of urgent and visible crises. ²⁷ The Institute of Medicine lamented in the 1980s that the United States had “allowed the system of public health activities to fall into disarray.” ²⁸ The notion that traditional public health strategies such as surveillance, environmental modifications, and risk factor control could also be deployed to combat chronic diseases gained currency only toward the end of the 20th century.

The trailblazing initiatives of the New York City Department of Health and Mental Hygiene (DOHMH) demonstrate how municipal agencies can be platforms for innovation in public health as the demands of urban populations evolve. ²⁹ Starting in 2002, in response to increased attention to the leading causes of death in the modern era, the health department leveraged epidemiology to inform policy‐based initiatives in chronic disease. Notable examples were the elimination of trans fats from restaurants, mandates that restaurants post calorie information on menus, and a tobacco control program that included a tax increase, a smoke‐free air law, antitobacco advertising, and smoking cessation services. Realizing that addressing the chronic disease burden required closer collaboration with the health care system, the department also launched public health “detailing” to primary care providers (i.e., outreach efforts intended to deliver educate physicians about key prevention initiatives), ³⁰ created a diabetes registry, and developed a public health electronic health record. Critical to these innovations were strong information systems, expertise in communications, policymaking authority, and political support.

Today, chronic disease surveillance and prevention is a mainstay for municipal health departments. ³¹ The Baltimore City Health Department, for instance, has specific initiatives for the prevention of asthma, cancer, diabetes, and cardiovascular disease—central focuses shared by hundreds of other municipal public health agencies.

Implicit in the efforts of DOHMH and other city health departments pivoting in response to the epidemiological transition was the understanding that, much like the contagions of prior centuries, the prevalence and distribution of chronic disease is not simply biological but socially rooted as well. High blood pressure, diabetes, and high cholesterol are functions not only of genetic predisposition but also of the restaurants where people eat, the food available to them, and their economic means to adopt a healthy lifestyle. Identifiable through research and modifiable through targeted policies, these nonmedical determinants of disease became cemented within the province of public health.

Urban Disparities and Health Equity

Just as industrialization led to the urban working class suffering disproportionately from infectious diseases in the 1800s, the forces influencing urban health today systematically disadvantage certain populations, especially racial and ethnic minorities and low‐income communities. A recent study of the 30 most populous US cities found that the Black‐White disparity in mortality increased in more cities than it decreased in, despite improvements in overall mortality rates. In both New York and Chicago, more than 3,500 excess Black deaths were observed annually relative to Whites. ³² The factors underpinning this life expectancy gap are complex. A study of this disparity in Washington, DC, demonstrated that the gap—which has markedly widened in recent years—is driven by deaths due to heart disease, homicide, cancer, and unintentional injury, suggesting potential upstream drivers such as disparities in obesity, physical activity, tobacco use, and access to cancer screening as well as safe living environments. ³³

The drivers of such disparities have been classified in several ways. The unifying feature of these frameworks is that some causes, such as health insurance or access to primary care, are more proximal while others, such as access to healthy food, are more distal. Many of these more distal causes are grouped under the social determinants of health, which are widely used to explain differential health outcomes in cities. ³⁴ , ³⁵ However, even more fundamental structural drivers, such as the American history of structural racism, are central to understanding urban health disparities.

The practice of redlining—a discriminatory practice in which minoritized individuals were systematically denied financial services such as loans to purchase homes—provides an instructive example. Historic redlining led to residential segregation and crippled the ability of Black families to build intergenerational wealth. Recent evidence demonstrates its lasting impact on the health of urban minorities. One study of nine major cities found strong associations between historically redlined neighborhoods and current‐day prevalence of cancer, asthma, poor mental health, and lack of health insurance. In some cities, residents in historically redlined areas were almost twice as likely to be in poor health than counterparts in non‐redlined areas. ³⁶ Another study demonstrated a similar association with preterm birth, further supporting historical redlining as a structural determinant of health outcomes. ³⁷

Another driver of urban health inequities that deserves special attention is growing income and wealth inequality. The relationships among income, poverty, and health outcomes are well established. ³⁸ , ³⁹ Growing within‐city income inequality ⁴⁰ portends worsening health inequality—both directly, as low‐income populations are further marginalized, and indirectly, as lower social mobility and economic opportunity influence health behaviors ⁴¹ and the increasing concentration of wealth consolidates political power exercised to benefit the rich at the expense of the poor. ⁴² Ultimately, these and other forces underpinning urban health inequities demand that we grapple with the overarching systems of power and privilege that entrench inequities. ⁴³

Environmental and Climate Threats for Urban Populations

The relevance of environmental factors to urban health has long been apparent. The prevalence of asthma in urban children, particularly socioeconomically disadvantaged youth, is a classic example because hygiene, ambient air pollution, and early life exposures to microbes and airborne allergens shape the pathophysiology of asthma. ⁴⁴ More generally, air pollution has consistently been associated with all‐cause, cardiovascular, and respiratory mortality. ⁴⁵ At a national level, the Clean Air Act and the National Ambient Air Quality Standards played important roles in regulating air quality. ⁴⁶ Municipalities have also experimented with different approaches to policy and private sector engagement to influence air quality, with mixed and often temporary effects on population health. ^{47 ‐ 49}

At the core of these efforts is the understanding that the social, economic, and political context—including housing, industry, and regulations—deeply influence the environment, including the air we breathe, which in turn profoundly affects health. Mitigating the root causes of environmental health risks, therefore, demands moving upstream of the environment itself. The historic water crisis in Flint, Michigan, demonstrates this notion in the modern era. While discourse has often focused on the failure of public health agencies to identify and address the drinking‐water contamination, the stage was set by a context that predated these proximal causes. The city's gradual financial decline prompted the cost‐cutting decision to switch water sources, while decades of infrastructure neglect allowed for pipe corrosion. ⁵⁰ While the poor health outcomes of the 140,000 adults and children exposed to lead motivated cities to evaluate their water supplies, Flint's experience should also serve as a broader signal to other cities that environmental emergencies result from common circumstances (i.e., disinvestment in municipal utilities due to budgetary constraints), which cascade into catastrophe.

Looking forward, environmental risks will be magnified by climate change, which poses a broader and evolving set of health threats that will disproportionately harm vulnerable populations. ⁵¹ As carbon emissions and other human activities continue to accelerate climate change, cities will be subject to more severe weather events, including storms and floods, and higher temperatures. In addition to their acute risks, which include traumatic injury and death, severe weather events disrupt utilities, transportation systems, and health care infrastructure, and they mobilize pathogens or toxins from waste reservoirs. ⁵² Higher urban temperatures also have multiple consequences for health, including dehydration, heat stroke, ⁵³ kidney disease, ⁵⁴ and worse health outcomes for existing conditions. Decarbonizing the US health sector, lobbying the international community to slow the pace of climate change, and building climate‐resilient health care infrastructure are urgent priorities to secure the future of urban health. ⁵⁵ , ⁵⁶

Behavioral Health in Cities

Public health institutions have largely focused on the primary drivers of mortality, from sanitation to smoking. While increased life expectancies globally owe much to these efforts, prioritizing mortality reduction has often overshadowed the sources of morbidity that may not shorten the life span but dramatically reduce quality of life. ⁵⁷ An important consequence of this fact has been the relatively little attention that public health agencies have paid to mental and behavioral health. Urban populations tend to experience higher rates of behavioral health conditions than rural populations, including depression, anxiety, substance use disorder, schizophrenia, and other diseases. ⁵⁸ , ⁵⁹ Access to mental health care and treatment services also tend to be limited for many urban populations, in severely inequitable ways. ⁶⁰ , ⁶¹ The COVID‐19 pandemic added insult to injury, causing significant increases in depression, anxiety, and psychologic distress in cities around the world, both among the general population and in special groups including adolescents and health care workers. ⁶² , ⁶³ , ⁶⁴ , ⁶⁵ City‐run crisis mental health services saw unprecedented volume in the early months of the pandemic, as both public and private mental health providers failed to manage surging demand. Given that ongoing climate change will increase the frequency of natural disasters and epidemics, which each take their own toll on mental health for affected populations, the need for greater behavioral health capacity will only grow.

The frequent exclusion of mental health from public health is particularly concerning given evidence that municipal‐level involvement in mental health can have a demonstrable impact. When local health departments take active roles in mental health prevention, promotion, and coordination, people with mental illness or substance use—especially Black adults and Medicaid enrollees—tend to experience better health outcomes, including fewer substance use– and suicide‐related emergency department visits, preventable hospitalizations, and hospital readmissions. ⁶⁶ , ⁶⁷ , ⁶⁸ , ⁶⁹ Unfortunately, most local health departments do not engage in key mental health activities. ⁷⁰ The opportunities for collaboration between behavioral health agencies and public health departments are significant, but remain untapped. ⁷¹

Constraints for Local Health Departments

Despite the magnitude of these challenges, municipal health agencies face significant obstacles in the pursuit of their mission. Chief among these is chronic underfunding. At a national level, the share of health care expenditures spent on public health has fallen in recent decades, leaving fewer and fewer dollars to trickle down to municipal health. ⁷² Despite evidence that greater local health department expenditure is associated with better health outcomes, ⁷³ local health department budgets are generally inadequate and highly tenuous. Years after the Great Recession, local health departments nationwide continued to report significant budget cuts, staffing reductions, and programmatic restrictions. ⁷⁴ , ⁷⁵ One report found that, over the past decade, the public health workforce has shrunk by roughly 56,000 positions due to funding issues; many of those losses are at the municipal level. ⁷⁶ Underinvestment in these agencies has been criticized for crippling pandemic preparedness in advance of the COVID‐19 pandemic. ⁷⁷ , ⁷⁸

Due in part to the absence of rigorous federal standards, municipal health departments vary widely in their activities, organization, and authority. ⁷⁹ Voluntary Centers for Disease Control and Prevention accreditation pathways for health departments have certified only a small fraction (300 of approximately 3500) of local health departments. In fact, some major US cities, such as Atlanta, lack city health departments altogether. The lack of uniformity not only makes it challenging to ensure minimum standards but also complicates intergovernmental coordination, especially with state and federal actors, a weakness that was especially costly during the COVID‐19 pandemic. For example, in February 2020, just before New York City became the first COVID‐19 epicenter in the United States, Governor Andrew Cuomo suspended the city's traditional legal powers to regulate public health threats and gave broad powers to the state government. Around the same time, it became clear that the city would not be able to rely on the federal government for guidance and resources related to COVID‐19 testing—despite that support having been a clear expectation during prior pandemic planning efforts.

Finally, municipal health departments are politically constrained. The roles of public health leaders versus elected officials are often vague and overlapping, setting the stage for conflict or misalignment. Many leaders of local health departments are appointed by politicians with partisan views that sometimes diverge from evidence‐based practice, a conflict that has become more consequential as public health measures are increasingly politicized. While the COVID‐19 pandemic placed this tension into stark relief with debates over masking and distancing and attacks on public health officials, public health has long been subject to polarization. ⁸⁰ For instance, Mayor Michael Bloomberg's policy to limit the serving size of sugary drinks became the target of partisan attacks, raising questions about the role of government and public health regulation (e.g., “nanny state” overreach) versus individual liberty and responsibility. ⁸¹

While these financial, bureaucratic, and political factors constrain the impact of municipal health departments, they have also encouraged creativity and innovation in urban public health, fostering the emergence of evidence‐based strategies.

Promising Strategies for Change

Surmounting these challenges will require cities to grapple with the structural determinants of urban health, including systemic racism and wealth inequality, to meet communities where they are, and to bridge the gap between health care and public health.

Addressing Structural Determinants

The health of populations is determined largely by the “conditions in which people are born, grow, live, work, and age.” ⁸² These factors are especially important in cities, where social conditions often systematically harm disadvantaged populations through structural violence. ⁸³ Fortunately, evidence‐based policies exist at the municipal level for cities to combat and prevent this harm by reshaping the conditions that cause it.

Managed by the de Beaumont Foundation and Kaiser Permanente, the CityHealth project identified a comprehensive set of such policies across nine categories: earned sick leave, universal prekindergarten, affordable housing, complete streets, alcohol sales control, youth tobacco control, smoke‐free indoor restrictions, food safety and inspection ratings, and healthy food procurement. ⁸⁴ That many of these categories focus on children and adolescents reflects the potential of municipal policies to promote youth well‐being, which is closely linked to better long‐term medical and financial outcomes. ⁸⁵

Selected laws in each CityHealth category have a demonstrated impact on health outcomes, mediated by the socioeconomic factors that they directly affect, and sometimes offer positive returns on investment for municipalities. ⁸⁶ For example, laws requiring employers to offer paid time off for illness or injury for employees, children, or parents have been associated with lower rates of infectious disease transmission ⁸⁷ as well as increased productivity, generating significant savings (from net reductions in absenteeism) while improving health. ⁸⁸ Model cities for earned sick leave policies include Albuquerque, Denver, Los Angeles, and San Diego. However, only a fraction of big cities have adopted such policies. ⁸⁹ Similar cases exist in other areas. Inclusionary zoning policies (such as those in Chicago and Los Angeles) that provide affordable housing for disadvantaged families to move to low‐poverty areas have been associated with improved health and economic outcomes. ⁹⁰ , ⁹¹ , ⁹² Restrictions on the use of trans fat in New York led to fewer hospitalizations for heart attack and stroke, saving lives and money. ⁹³ Municipal taxes on tobacco can significantly reduce smoking rates—producing dramatic reductions in mortality while also producing cost savings from lower health care expenditures. ⁹⁴ In fact, interventions that alter the environment are far more likely to generate net cost savings than individual‐level or clinical interventions, making them an important and accessible tool for resource‐constrained municipalities. ⁹⁵ Other efforts—such as enhancements to the physical layout and amenities of cities to increase walkability, green space, and opportunities for fitness (e.g., New York City's Active Design Guidelines and “built environment” initiatives ⁹⁶ )—may not be cost saving but still produce some returns (e.g., lower future health care spending from better control of exercise‐sensitive conditions such as diabetes) that partially offset the required investment.

Of all the health determinants in urban contexts, poverty has long been identified as the most potent driver of poor health because it lies at the root of all other social and economic conditions. Rudolf Virchow's report on the 1848 typhus epidemic in Germany highlighted that combating the disease required not medical solutions but rather social reconstruction, addressing poverty through full employment, higher wages, and universal education. ⁹⁷ Today, low income continues to limit access to nutritious food, safe housing, quality education, and other basic assets upon which good health is dependent. Poverty reduction is, therefore, an imperative for any effort to improve urban health.

In the spirit of Virchow's revolutionary proposals, modern cities can use policy to simultaneously address poverty and disease. One straightforward approach is direct cash transfers. Conditional cash transfers, which redistribute cash to low‐income households that meet certain requirements, have been associated with poverty reduction and improvements in growth and nutrition among children, preventive health service use, and vaccination coverage. ⁹⁸ Some more recent efforts have tested unconditional cash transfers, sometimes observing improvements in important outcomes, including children receiving necessary medications and attending school. ⁹⁹ During the COVID‐19 pandemic, municipalities in Ontario, Canada, ¹⁰⁰ and New York tested unconditional cash transfers. In New York City, where the initiative was spearheaded by the public safety‐net hospital system, the cash transfers were used for food, shelter, and supplemental oxygen for home use to support COVID‐19 recovery. ¹⁰¹

Cash transfers and other poverty reduction measures can be considered to various degrees in cities, designed based on the levels of economic inequality and prevailing political sentiment. The potential for tax policy—including expansions of the earned income and child tax credits as well as proposed taxes on wealth—to redistribute resources must be part of this conversation given the deep connection between wealth accumulation and population health and the persistence of racial wealth gaps that constrain health equity. ¹⁰² , ¹⁰³ , ¹⁰⁴ Baby bonds, publicly funded investment accounts created by the government for newborns, are a specific example of an intervention to redress the racial wealth gap, and have already been enacted in Washington, DC, and Connecticut. ¹⁰⁵ Such policies can be coupled with participatory budgeting so communities can help decide how public funds are allocated, increasing agency and directing dollars to what each individual community needs most. ¹⁰⁶

The underlying rationale for pursuing these policies as part of population health strategy is best articulated by the “vital conditions” framework developed by the Rippel Foundation's ReThink Health Initiative, which center the separate but interdependent conditions that all people depend on to reach their full potential for health and well‐being (Figure 1). ¹⁰⁷ These include basic safety needs, lifelong learning, meaningful work and wealth, humane housing, and reliable transportation. Each policy discussed in this section helps ensure one or more vital conditions are met for urban populations.

Figure 1.

Vital Conditions for Health and Well‐Being [Colour figure can be viewed at wileyonlinelibrary.com]

Reprinted from Milstein B, Payne B, Kelleher C, Homer J, Norris T, Roulier M, Saha S. Organizing around vital conditions moves the social determinants agenda into wider action. Health Affairs Forefront. https://www.healthaffairs.org/content/forefront/organizing‐around‐vital‐conditions‐moves‐social‐determinants‐agenda‐into‐wider‐action. Source: Rippel Foundation.

Community‐Level Engagement

In the effort to identify and address both medical and social determinants, mounting experience indicates the importance of a community‐level presence for public health in our urban communities.

Internationally, several countries have built deep community engagement into their public health and primary health care systems. In Costa Rica, for example, the Ministry of Health embeds a public health official in every community with resources and staff for infection control, malnutrition, environmental hazards, and sanitation. Further, every Costa Rican is assigned to a local multidisciplinary care team, which provides primary care and performs public health functions. ¹⁰⁸ This model has been linked to Costa Rica's success in improving longevity faster than other nations. ¹⁰⁹

Domestically, New York City recently established a Public Health Corps program to “expand the public health workforce, strengthen community health infrastructure, and promote health equity for the communities hit hardest by the COVID‐19 pandemic.” ¹¹⁰ Community health worker (CHW) programs, in which local residents are trained to provide tailored support for fellow community members, have been shown to address unmet social needs, improve chronic disease control and mental health, reduce avoidable hospitalizations, and deliver positive return on investment. ¹¹¹ , ¹¹² , ¹¹³ , ¹¹⁴ Leveraging their high levels of trust in their communities, CHWs also played important roles during the COVID‐19 pandemic, initially with contact tracing and later with vaccinations, in areas as diverse as Southern California, Delaware, and inner‐city Boston. ¹¹⁵ Motivated by the strong evidence base and building on the successful Test & Trace Corps during the COVID‐19 pandemic, New York's Public Health Corps initiative will train and embed hundreds of CHWs in communities throughout the city to address social needs. It will also offer grants to community‐based organizations and integrate with local care delivery systems (e.g., NYC Health + Hospitals, federally qualified health centers), stitching together and strengthening community health infrastructure to simultaneously advance population health and equity. The city of Baltimore recently launched a similar effort, the Baltimore Health Corps, as a pilot program to recruit, train, and employ 275 CHWs who were unemployed and living in neighborhoods hit hardest by COVID‐19. ¹¹⁶ These community‐based health corps, which have gained currency in several cities (e.g., Detroit) during the pandemic, ¹¹⁷ are uniquely suited for a hyperlocal approach to epidemic response and community empowerment. ¹¹⁸

Community‐level engagement is necessary because place‐based factors profoundly influence health outcomes. ¹¹⁹ The NYC Neighborhood Health Action Centers—operated by the NYC Health Department—serve as a place‐based model for integrating health and social care to serve vulnerable populations at both the individual and community levels. ¹²⁰ Established to improve health in neighborhoods with disproportionate burdens of premature mortality, these action centers colocate clinical services and community‐based resources, a linkage‐based approach that has been shown to improve health outcomes. ¹²¹ Surveys in East Harlem demonstrate how these centers can become a hub for medical and social programs, services, and referrals for local residents. ¹²² They also function as entry points to engage low‐income minority communities for community‐based organizations and other agencies, helping build a culture of health at the neighborhood level. ¹²³

Finally, cities can organize to empower and direct local health departments as part of broader antiracist efforts. The Wisconsin Public Health Association pioneered local declarations of racism as a public health crisis, which have since been adopted by several counties and cities. ¹²⁴ Although these declarations alone may be symbolic, they are ideally paired with substantive action to advance equity, including new investments in underserved communities and policies to address police brutality (e.g., police oversight commissions), housing segregation, and incarceration, among other issues. ¹²⁵ An essential prerequisite to engaging historically overlooked communities is admitting past harm done to them, recognizing racism as a root cause, and paving a path toward truth and reconciliation. These municipal resolutions are a first step in that direction.

Municipal Agencies as Providers of Care

In a time of rapid innovation in care delivery for vulnerable populations, city health departments can also contribute to population health through the direct provision or coordination of medical care. This tradition has a long history, dating back to the publicly financed and operated city health clinics of the early 20^th century. In 1977, the Robert Wood Johnson Foundation launched the Municipal Health Services Program, which invited large US cities to devise networks of clinics to provide primary care services in areas with poor access to care, with the goal of addressing the fragmentation of care in public hospitals and other public facilities. Five cities joined, and the program was shown to increase access for many marginalized groups and reduce medical expenditures for Medicare beneficiaries. ¹²⁶

NYC Health + Hospitals, the largest public health system in the country, provides a model for proactive approaches to municipal health care delivery that reduce avoidable suffering for populations that rely on the safety net. Through thoughtful stratification of urban residents, high‐quality community‐based care, data‐driven outreach, and a commitment to meet patients where they are, the H+H experience is a testament to how municipal agencies can actively manage population health. ¹²⁷ , ¹²⁸ Municipal agencies have certain advantages in this area relative to private delivery systems. For example, public provider systems can more easily be payer agnostic in their initiatives, increasing clinician buy‐in and facilitating all‐payer models to manage care and bear risk. ¹²⁹ Resource‐constrained but free of profit motives and investor pressures, public systems may also be more likely than private systems to invest in low‐margin service lines with high value for patients, such as primary care ¹³⁰ and home visits, ¹³¹ which in turn create a platform to engage patients across the full range of their physical and mental health. ¹³² Similarly, public systems may take a longer view than private systems, enabling investments in evidence‐based but underutilized interventions that deliver returns not in months but in years, such as nurse‐family partnerships. ¹³³ , ¹³⁴

Finally, municipal agencies may help expand access to care for urban residents lacking health insurance. Healthy San Francisco, for instance, provides access to health services for more than 50,000 city residents, including the uninsured and undocumented, and is operated by the San Francisco Department of Public Health. San Francisco chose to pair this program with a unique municipal requirement that employers contribute financially to employees’ health care costs. ¹³⁵ My Health LA and NYC Care provide similar functions in Los Angeles and New York City, respectively, for people who cannot afford health insurance or are ineligible—for instance, due to immigration status.

By returning to their roots in direct service provision, city public health agencies can deepen their presence in communities and ground their population‐level efforts in the lived experiences of the individuals they serve.

The Future of Urban Health

From the sanitation revolution to the epidemiologic transition of the 20^th century to the recent COVID‐19 pandemic, the history of public health in cities has been marked by innovation and adaptation. The evolving health challenges cities will face in coming decades will similarly require new approaches to financing, delivering, and organizing public health. Our aspirations for the future of urban health are shaped by the major challenges we identified and the promising strategies that give us hope in the potential of cities to meaningfully advance human health. Our vision centers the pursuit of health equity and social justice, emphasizes the place‐based factors that promote or constrain health, and requires that we bridge public health and health care to better serve marginalized populations. Achieving this vision will demand greater investment, technological advancements, and linking local efforts to a broader global commitment to population health. Municipal health departments and policies will be critical in this endeavor, especially to impact the structural factors constraining urban health.

Investing in Public Health

A healthier future for urban populations demands, above all, massive investments in public health. Before the pandemic, the share of US health spending dedicated to public health was rapidly declining, undermining prevention, preparedness, and other key functions. ¹³⁶ In 2018, public health spending totaled approximately $286 per capita, compared to over $10,000 on health care. ¹³⁷ Most public health spending in the US comes from state and local governments, meaning municipal health departments are a key channel through which public health dollars are used. ¹³⁸ The additional strain the COVID‐19 pandemic placed on city health departments makes further investment even more urgent. ¹³⁹

A recent systematic review found that, in high‐income countries, the median return on investment across 29 local public health interventions (excluding nationwide efforts) was 4.1 to 1, with a median cost‐benefit ratio of 10.3. ¹⁴⁰ If so many city‐level public health efforts save more money than they cost, why do we invest so little in them? Tight municipal budgets, long time horizons for future returns, and the invisibility of impact are just a few of many reasons. ¹⁴¹ , ¹⁴²

A central issue is the “wrong pocket” problem, wherein public health agencies may make investments in prevention, but the downstream savings from those investments (e.g., lower health care expenditures) are captured by other entities, including individuals, their health insurers, or other government agencies. ¹⁴³ , ¹⁴⁴ Solving this “wrong pocket” problem would not just increase investment in public health but also help scale interventions that improve health and social equity across generations. For instance, programs and policies to support maternal and infant health, such as nurse home visiting, have longer‐term benefits on health spanning the life course—and for multiple family members, spanning generations—beyond the immediate support they provide. ¹⁴⁵ , ¹⁴⁶ , ¹⁴⁷ , ¹⁴⁸

Fortunately, innovative financing mechanisms exist to address these hindrances. Social impact bonds as well as pay‐for‐success and value‐based payment models have been used in public health to attract socially minded investors and reward organizations that address social determinants and demonstrate improved health outcomes and cost savings. ¹⁴⁹ , ¹⁵⁰ While these ideas have had limited success and scale to date, newer methods—such as “public health bonds”—are emerging that may better align incentives and allow public health agencies to share (e.g., with health care payers like Medicaid agencies or health insurance companies) the savings they generate. ¹⁵¹ Returning to the “vital conditions” framework, these financing mechanisms capitalize on the notion that meaningful investments in vital conditions reduce the demand for expensive “urgent services” (e.g., acute care for illness or injury, unemployment and food assistance, crime response, homeless services), enabling a self‐reinforcing cycle of continued investment (Figure 2). ¹⁰⁷ , ¹⁵²

Figure 2.

A Well‐Being Portfolio Balances Vital Conditions and Urgent Services. [Colour figure can be viewed at wileyonlinelibrary.com]

Reprinted from Milstein B, Payne B, Kelleher C, Homer J, Norris T, Roulier M, Saha S. Organizing around vital conditions moves the social determinants agenda into wider action. Health Affairs Forefront. https://www.healthaffairs.org/content/forefront/organizing‐around‐vital‐conditions‐moves‐social‐determinants‐agenda‐into‐wider‐action. Source: Rippel Foundation.

More fundamental structural changes to public funding sources have more promise. For example, the US Department of Health and Human Services Public Health 3.0 initiative called for structured, cross‐sector partnerships at the community level, enabled by the blending and braiding of funding sources across health care and social services to ensure that savings are captured and reinvested over time. ¹⁵³ Allegheny County in Pennsylvania served as an important model for this type of multisectoral collaboration. Others have proposed community health trusts as an approach to construct local public‐private partnerships between public health agencies and hospitals to finance community‐based prevention. ¹⁵⁴ As cities continue to experiment to define the optimal financing methods for public health, they should also focus on better communicating existing evidence of strong return on investment for public health interventions, as the immense societal value of these efforts is beyond dispute.

Leveraging Data and Novel Technology

Today, the promise of big data remains unrealized in public health. We collect more health data than ever before in human history, but local health departments suffer from a wide gap between raw data and actionable information. Although the collection of vital statistics like infant mortality and smoking rates fueled life‐saving population health campaigns in the past, the incremental benefit of additional data has diminished in the modern era, where data‐driven insights that can inform real‐time decisions and policy change are often lacking.

In the coming decade, the advancement of data infrastructure in major cities could transform municipal approaches to population health. Recently, services such as the City Health Dashboard have begun to provide standardized metrics of health and drivers of health for large US cities. Data is currently available for 35 metrics and over 750 cities through this dashboard. ¹⁵⁵ In the future, every city should have a real‐time publicly available dashboard with detailed data describing measures not only of health but also of health‐related social needs, all stratified on race, ethnicity, and other demographics. ¹⁵⁶ However, enhancing the reliability, completeness, and availability of such data is alone insufficient. We must adopt summative metrics that synthesize these vast data sets into meaningful and interpretable signals about how and where to allocate resources to generate the largest improvements in population health per dollar spent. Health‐adjusted life expectancy (HALE) is an example of such a metric that dismantles the false dichotomy between clinical care and public health and recenters the common goal of longer, healthier lives. ¹⁵⁷ Broad adoption of metrics like HALE could be used to prioritize initiatives, allocate budgets, target interventions, and hold governments accountable for their investments and success in advancing population health.

In addition to equipping governments with actionable information, technology also offers the potential to help individuals understand and contextualize their health‐related risks and modify their behaviors accordingly. The rise of “smart cities”—which will collect and analyze vast quantities of data through sensors, devices, and wireless communication networks—is one example. Smart cities will afford municipal health departments new opportunities for public health surveillance while also enabling more direct engagement of residents through smartphone applications and wearable devices. ¹⁵⁸ Importantly, strong privacy safeguards will be critical to prevent potential unintended consequences from increased surveillance capabilities.

The COVID‐19 pandemic brought both of these notions to the fore. Cities across the world focused the attention of the public, elected officials, and public health leaders on key metrics, such as cases, hospitalizations, and deaths, to direct decision making. Meanwhile, local health departments also attempted to help individuals assess their personal risk (e.g., color‐coded alert levels). These efforts lay the foundation for how data may inform public health in the post‐COVID‐19 era. For example, rapid turnaround times between data collection, interpretation, and response during the pandemic provide a model for acting nimbly to address other rapidly evolving public health challenges, like the overdose crisis.

The pandemic also illustrated the capacity for municipal innovation, as cities developed mobile applications for case detection and contact tracing, algorithms to predict spread, and analytics to stretch limited resources as far as possible. ¹⁵⁹ , ¹⁶⁰ , ¹⁶¹ In New York City, the health department sought to identify emerging hotspots for proactive intervention. The department developed a real‐time surveillance system, powered by the publicly available SaTScan software for space‐time scan statistics, to detect spatiotemporal clusters where COVID‐19 diagnoses were increasing relative to elsewhere in the city, adjusted for testing rates. ¹⁶² This system facilitated early detection and intervention to help interrupt further transmission.

Municipalities can build on these successes by repurposing these technologies for noncommunicable disease and underlying drivers of physical, mental, and social well‐being, orienting summative metrics like HALE as the North Star for these efforts. Further development and robust evaluation will be important at both the population and individual levels, especially with the proliferation of artificial intelligence–based algorithms that could perpetuate bias if not carefully designed and tested. ¹⁶³

Coalitions of Cities

Over the next decade, we expect city health departments to play a leading role in the advancement of human health. We can accelerate their success by forming and leveraging coalitions of global cities as a powerful force for health.

In urban health, cities are the laboratories for innovation, and growing international collaboration among cities is needed to facilitate the identification and sharing of best practices. The Big Cities Health Coalition (BCHC) is a useful domestic model. A forum for leaders of the country's 30 largest metropolitan health departments, BCHC fosters the exchange of strategies and collects data from member health departments to better describe challenges, such as workforce management. ¹⁶⁴ , ¹⁶⁵ The World Health Organization's Healthy Cities Network is a similar forum for European cities. ¹⁶⁶ However, the sharing of best practices does not stop at the boundaries between continents. Consider Thrive London, a citywide movement to improve the mental health and well‐being of Londoners. Cross‐city collaboration among the mayor, the London Health Board, the Healthy London Partnership, and the National Health Service has facilitated the participation of more than 600,000 people in projects, events, and activities including suicide prevention training, mental health first‐aid training, online webinars, and sudden bereavement support. In the wake of social distancing during the COVID‐19 pandemic, a signature initiative of Thrive London was the Campaign to End Loneliness, which recognizes that promoting mental health requires moving beyond only clinical diagnoses and toward population‐wide engagement on issues that affect all people who live in cities, not just those at highest risk or most affected. As cities around the world consider how to tackle the epidemic of loneliness and foster greater social connectedness, they can look to such models.

International coalitions of cities can do more than share best practices; they can also serve as platforms to organize for large‐scale policy change. During the COVID‐19 pandemic, this approach was used to advocate for global vaccine equity. Health ministers, commissioners, and mayors from Buenos Aires, Sao Paulo, Montevideo, Toronto, Paris, London, Madrid, and New York City collectively signed a letter addressed to all G20 nations, calling for more equitable access to vaccines in the global south. ¹⁶⁷

Similar approaches could be considered for other public health priorities, harnessing the power and experience of municipal health departments to advance global health justice. Consider climate change as one example. Cities around the world are the primary drivers and victims of climate change and its consequences. Some have taken important steps. New York City was one of the first cities to set carbon mitigation goals as part of Mayor Bloomberg's 2007 PlaNYC initiative. In 2014, New York City committed again to reduce greenhouse gas emissions by 80% by 2050. This policy is projected to prevent between 160 and 390 premature deaths and 460 hospitalizations and emergency department visits for respiratory and cardiovascular disease each year, saving $3.4 billion annually. ¹⁶⁸ Most of the benefit will accrue to low‐income neighborhoods, where, for instance, 10 times more asthma‐related emergency department visits will be avoided than in the wealthiest neighborhoods despite similar declines in ambient particulate matter. However, local climate action is insufficient to bend the arc of rising global temperature. Where international efforts such as the Paris Climate Agreement have faced significant obstacles, coalitions of cities could make collective commitments to reduce emissions and address climate change as a public health issue, recognizing their interdependence and holding each other accountable in pursuit of a common goal.

Conclusion

Over the past century, city health departments fought tuberculosis, conquered the spread of waterborne disease, vaccinated millions, and birthed the modern practice of public health. They tackled the scourge of smoking, curtailed global pandemics, and made it their mission to protect the well‐being of broad and diverse populations. Held accountable for responsibilities far outpacing their resources, they acted as stewards of urban health during times of rapid economic development, growing political pressures, and unforeseeable medical threats.

Yet, their potential remains largely untapped. As more and more people spend more and more of their lives in cities, the importance of municipal action will only grow, not just for population health but for our economy, for our political institutions, and for our social fabric. Unleashing cities’ full potential to be a positive force for justice and societal progress demands that we consider not only the roles they played in the past but also the roles they could play in the future. On the heels of a generational pandemic, cities worldwide face an unparalleled moment of possibility. Seizing it will require not just imagination and innovation, but also investment and infrastructure.

Conflict of Interest Disclosures: Dr. Chokshi was formerly the commissioner of the New York City Department of Health and Mental Hygiene. Mr. Gondi received fees from the New York City Department of Health and Mental Hygiene outside the submitted work.