Overview
The rural-urban commuting area (RUCA) codes classify U.S. census
tracts using measures of population density, urbanization, and
daily commuting. The most recent RUCA codes are based on data from
the 2000 decennial census. The classification contains two levels.
Whole numbers (1-10) delineate metropolitan, micropolitan, small
town, and rural commuting areas based on the size and direction of
the primary (largest) commuting flows. These 10 codes are further
subdivided to permit stricter or looser delimitation of commuting
areas, based on secondary (second largest) commuting flows. The
approach errs in the direction of more codes, providing flexibility
in combining levels to meet varying definitional needs and
preferences.
The 1990 codes are similarly defined. However, the Census
Bureau's methods of defining urban cores and clusters changed
between the two censuses. And, census tracts changed in number and
shapes. The 2000 rural-urban commuting codes are not directly
comparable with the 1990 codes because of these differences.
An update of the Rural-Urban Commuting Area Codes is planned for
mid-2013.