Measuring Rurality: Rural-Urban Continuum Codes

Measuring Rurality Briefing Room What is Rural? Metro/Nonmetro Definitions in 2003 2004 County Typology Codes Commuting Zones and Labor Market Areas Rural-Urban Continuum Codes Urban Influence Codes Data Options for Rural Research

Rural-Urban Continuum Codes form a classification scheme that distinguishes metropolitan (metro) counties by the population size of their metro area, and nonmetropolitan (nonmetro) counties by degree of urbanization and adjacency to a metro area or areas. The metro and nonmetro categories have been subdivided into three metro and six nonmetro groupings, resulting in a nine-part county codification. The codes allow researchers working with county data to break such data into finer residential groups beyond a simple metro-nonmetro dichotomy, particularly for the analysis of trends in nonmetro areas that may be related to degree of rurality and metro proximity.

All U.S. counties and county equivalents are grouped according to their official metro-nonmetro status announced by the Office of Management and Budget (OMB) in June 2003, when the population and worker commuting criteria used to identify metro counties were applied to results of the 2000 Census. Metro counties are distinguished by population size of the Metropolitan Statistical Area of which they are part. Nonmetro counties are classified according to the aggregate size of their urban population. Within the three urban size categories, nonmetro counties are further identified by whether or not they have some functional adjacency to a metro area or areas. A nonmetro county is defined as adjacent if it physically adjoins one or more metro areas, and has at least 2 percent of its employed labor force commuting to central metro counties. Nonmetro counties that do not meet these criteria are classed as nonadjacent.

Find the Rural-Urban continuum codes for the counties in your State.

In concept, the 2003 version of the Rural-Urban Continuum Codes is comparable with that of earlier decades. However, OMB made major changes in its metro area delineation procedures for the 2000 Census, and the Census Bureau changed the way in which rural and urban are measured. Therefore, the new Rural-Urban Continuum Codes are not fully comparable with those of earlier years. OMB's changes added some additional metro areas by no longer requiring that a metro area must have at least 100,000 population if its urbanized area has no place of at least 50,000 people. More importantly, simplifying the worker commuting criteria that determine outlying metro counties had the effect of both adding numerous new outlying counties to metro status while deleting a smaller number that were previously metro.

The Census Bureau made a radical shift in determining Rural-Urban boundaries by changing and liberalizing the procedures for delineating urbanized areas of 50,000 or more people, and abandoning place boundaries in measuring urban or rural population. The procedures used in defining Urbanized Areas were extended down to clusters of 2,500 or more people, based solely on population density per square mile. In this manner, lightly settled sections of municipalities were treated as rural and densely settled areas adjoining urban cores were treated as urban, regardless of whether they were incorporated or not. Thus "urban clusters" need not necessarily have at least one incorporated or unincorporated place of 2,500 population, and not all incorporated or unincorporated places of 2,500 population constitute urban clusters. On balance, these completely computerized techniques for identifying and bounding urban areas have enlarged the urban population. It is not possible to redefine Rural-Urban Continuum Codes for prior censuses in a manner consistent with those of 2003.

In earlier versions of the Rural-Urban Continuum Codes, metro areas with 1 million population or more were subdivided between central counties (Code 0) and fringe counties (Code 1). The Code 1 group has become much less meaningful in the last two censuses as more and more counties of large metro areas have been rated as central counties by OMB procedures. In 2000, only 1.6 percent of the population of large metro areas was in fringe counties. Therefore, this distinction has been dropped. Codes 0 and 1 have been combined, and the new code 1 represents all counties in metro areas of 1 million or more population.

All told, the 2003 Rural-Urban continuum code scheme includes 1,089 metro counties and 2,052 nonmetro counties. Independent cities of Virginia have been combined with their counties of origin.

This coding scheme was originated in 1975 by David L. Brown, Fred K. Hines, and John M. Zimmer, then of the Economic Research Service, for a report Social and Economic Characteristics of the Population in Metro and Nonmetro Counties: 1970. It was updated after both the 1980 and 1990 censuses, with a somewhat more restrictive procedure for determining metro adjacency. The versions based on the 1970, 1980, and 1990 Censuses are all found on this ERS website:

• Download the Rural-Urban Continuum Codes
• Description of codes for previous years