Table 1.
Variables used in the analysis
| Variable | Definition |
|---|---|
| Adult Sex Ratio | Ratio of males to 100 females aged 20 and older |
| Child-Woman Ratio | Ratio of children aged 0–4 to women aged 15–49a |
| Cropland Acreage | Sum of acres harvested for major crops and for land in fallow and failed crops, for 1880–1920; in 1930 and 1940, census tabulations of total cropland |
| Farmland Acreage | Number of acres of land in farms |
| Total County Acreage | Area of county, in acres |
| % Farmland in Crops | Cropland as a percentage of Farmland |
| % County Area in Crops | Cropland as a percentage of Total County Acreage |
| % Farmland | Farmland as a percentage of Total County Acreage |
| Mean Precipitation | Average annual precipitation, millimetersb |
| High Precipitation | Counties with Mean Precipitation greater than 465 millimeters |
| Mean Temperature | Average county temperature (mean of minimum and maximum), degrees Celsiusb |
| % Sand in Soil | Average percent sand in soilc |
| Depth of Topsoil | Average depth of topsoil layerc |
| Population Density | Persons per square mile |
| % Population Urban | Percent of total county population living in places of 2,500 persons or more |
| % in Ethnic Group in 1910 (Scandinavian, German/Eastern European, UK, Mexican) or 1990 (Hispano) | Percent of total county population either born in the place specified, or the child of at least one parent born in the place specified |
Source: All data are from the Great Plains Project Database (Gutmann 2005a, b; Gutmann et al. 1998).
The U.S. Census does not report five-year age groups for counties from 1880 through 1920. We have taken state-level five-year age groups and fitted them to counties for these years, while attempting to maximize the amount of information available in those years for other age groups. For example, in some years data are available for the proportion aged 21 and over, or for the proportion aged 18–49. In 1930, the census reports the number aged 35–44, and 45–54. For the child-woman ratio we have divided the number aged 45–54 in half to estimate the number aged 45–49.
Averages computed over 1900–1939 if data exist for that period, and over shorter periods if necessary.
Soil survey data averaged to the county level from late twentieth century sources.