Table 1. County-Level Characteristics.

Characteristic	Mean (SD)		P Value
	Medicaid Expansion States	Medicaid Nonexpansion States
States, No.	30a	19	NA
Counties included, No.
2010	912	994	NA
2011	902	989
2012	905	992
2013	923	985
2014	923	1013
2015	918	1012
2016	931	1029
US census region, %
South	21.9	84.1	<.001
Northeast	18.9	1.5	<.001
Midwest	39.3	11.5	<.001
West	20.0	2.9	<.001
Nonmetropolitan counties, %	48.0	50.9	.21
Residents aged 45-64 y per county in 2010, median (IQR)b	16 595 (9030-42 640)	11 114.5 (6514-25 225)	<.001
County residents aged 45-64 y without insurance, %
In 2010	14.6 (5.1)	19.5 (6.0)	<.001
Change in percentage, 2010-2016	7.3 (3.2)	5.6 (2.7)	<.001
County residents aged 45-64 y without insurance with income <138% of the federal poverty line, %
In 2010	35.6 (8.0)	44.9 (7.9)	<.001
Percentage change, 2010-2016	19.8 (5.5)	13.5 (3.9)	<.001
Demographic attributes in county residents aged 45-64 y in 2010, %
Female	51.2 (1.2)	51.5 (1.4)	<.001
Black	9.6 (11.1)	16.5 (14.0)	<.001
Hispanic	11.4 (12.0)	11.0 (16.2)	.57
Attributes of county residents in 2010, %
Unemployed adults	10.1 (2.5)	9.5 (2.3)	<.001
In poverty	14.4 (5.0)	16.6 (5.4)	<.001
With diabetes	8.5 (1.5)	9.7 (1.6)	<.001
With obesity	26.2 (4.6)	29.1 (4.2)	<.001
Smoking	17.1 (4.7)	18.9 (5.2)	<.001
County household income in 2010, median (IQR), $c	57 653.6 (49 490.3- 69 431.4)	50 369.4 (44 279.8- 57 251.0)	<.001
Clinicians per 100 000 residents in 2010
Primary care clinicians	78.3 (27.7)	65.7 (25.3)	<.001
Cardiologists	7.7 (6.4)	6.6 (5.3)	<.001

Abbreviations: IQR, interquartile range; NA, not available.

^aIncluded 29 states and Washington, DC.

^bSummary measure not weighted by county population.

^cIn 2016 dollars.