TABLE B-1 Methodologies Used to Define Rural Areas


Bureau of the Census Population Density

OMB Metropolitan, Micropolitan,a and Noncoreb Statistical Areas


Population density measured in units smaller than the county level.

Metropolitan and micropolitan areas measured at the county level.


More detailed measurement and analysis of the local community.

Assesses the extent to which a large city’s economic influence extends beyond its limit.

Urban/Metro Definition

Urbanized areas (UAs) include a central city and surrounding densely settled areas of at least 2,500 population that together have a population of 50,000 or more and a population density exceeding 1,000 per square mile. Urban clusters include freestanding towns of 20,000–49,000, 10,000–19,000, 2,500–9,999. Definitions applied in year 2000.

Core-based statistical areas (CBSAs) include metropolitan and micropolitan areas. Each metropolitan CBSA must have at least one UA of 50,000 population or more. Micropolitan CBSAs must have at least one urban cluster of 10,000–49,999. Nonmetropolitan areas can include micropolitan areas and noncore areas (what is thought of as rural). Definitions applied in year 2000.

IOM Determinations of Rural for This Report

Rural areas are considered those with 2,500 or less population.

Noncore nonmetropolitan areas outside metropolitan CBSAs.

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement