Nonmetro Counties Vary by Urban Size and Metro Proximity
New York City is a world apart from Hickory, NC, even though both are officially metropolitan (metro) areas. And nonmetropolitan (nonmetro) counties such as Washington County, MS, with a city of 41,000 people (Greenville) and densely settled countryside, differ greatly from sparsely settled Great Plains counties without an urban center and no more than several thousand residents each. Frequently though, researchers compare only metro versus nonmetro totals, either for brevity or because the data are only available as a dichotomy. However, counties are likely to vary systematically in their trends and characteristics by population size and—if nonmetro—by their amount of urbanization and whether they adjoin a metro area. To address this diversity, ERS developed the Rural-Urban Continuum Code to classify counties along a residential scale.
This nine-interval code allows a researcher to look at metro counties grouped by the population size of their metro area, and nonmetro counties by their amount of urbanization, if any. Nonmetro counties are also cross-classified by whether or not they are adjacent to a metro central county, on the premise that adjacent counties will typically show characteristics somewhat different from nonadjacent counties due to easier access to metro facilities and employment.
The Rural-Urban Continuum Code is used here to illustrate the percentage of people who were age 65 or older in 2000. The lowest incidence (11.4 percent) was found in metro areas of 1 million or more population. One key reason for this is that the largest metro areas are major gateways for immigrants who are disproportionately young adults or young families with children. Their addition to the population base thus reduces the share of older people.
In contrast, 17.7 percent of residents were age 65 years or older in nonmetro counties without an urban population and not adjacent to a metro area. Many of the counties in this group are farming areas that have long experienced high outmigration of young adults and declining or near stationary population with little infusion of immigrants. In such rural areas, social issues concerning older people are pertinent to a greater share of the population than is true in larger communities.
Between these two extremes, the percentage of people 65 and older generally rises with each step down the residential scale, with the exception of the category consisting of nonmetro counties that have 20,000 or more urban residents and are not adjacent to a metro area. Although most social and economic variables have at least one exception to a regular progression of increased or decreased values along the continuum scale, they usually have a substantial degree of overall association with the code categories. And that has made the Rural-Urban Continuum code useful in a variety of research.
Rural-Urban Continuum Codes, by John Cromartie, USDA, Economic Research Service, December 2020