Rural-Urban Continuum Codes

The 2023 Rural-Urban Continuum Codes distinguish U.S. metropolitan (metro) counties by the population size of their metro area, and nonmetropolitan (nonmetro) counties by their degree of urbanization and adjacency to a metro area. The division of counties as either metro or nonmetro, based on the 2023 Office of Management and Budget (OMB) delineation of metro areas, is further subdivided into three metro and six nonmetro categories. Each county and census-designated county-equivalent in the United States, including those in outlying territories, is assigned one of these nine codes. The codes allow researchers, policy makers, and others to view county-level data by finer residential groups—beyond metro and nonmetro—when analyzing trends related to population density and metro influence.

Developed in 1974, the Rural-Urban Continuum Codes have been updated each decade since (1983, 1993, 2003, 2013, 2023). Changes in the criteria used to define urban and metro areas over time has reduced the comparability of the Rural-Urban Continuum Codes over each of the past five decades. For the 2023 version, the threshold for urban area population was raised from at least 2,500 to 5,000 people, reflecting changes to urban area qualification introduced by the U.S. Census Bureau in 2020.

See the Documentation for details and a map of the codes.