NCHS urban-rural classification scheme for counties.

OBJECTIVES This report details the National Center for Health Statistics' (NCHS) development of the 2006 NCHS Urban-Rural Classification Scheme for Counties and provides some examples of how the scheme can be used to describe differences in health measures by urbanization level. METHODS The 2006 NCHS urban-rural classification scheme classifies all U.S. counties and county-equivalents into six levels--four for metropolitan counties and two for nonmetropolitan counties. The Office of Management and Budget's delineation of metropolitan and nonmetropolitan counties forms the foundation of the scheme. The NCHS scheme also uses the cut points of the U.S. Department of Agriculture Rural-Urban Continuum Codes to subdivide the metropolitan counties based on the population of their metropolitan statistical area (MSA): large, for MSA population of 1 million or more; medium, for MSA population of 250,000-999,999; and small, for MSA population below 250,000. Large metro counties were further separated into large central and large fringe metro categories using classification rules developed by NCHS. Nonmetropolitan counties were assigned to two levels based on the Office of Management and Budget's designated micropolitan or noncore status. The 2006 scheme was applied to data from the National Vital Statistics System (NVSS) and the National Health Interview Survey (NHIS) to illustrate its ability to capture health differences by urbanization level. RESULTS AND CONCLUSIONS Application of the 2006 NCHS scheme to NVSS and NHIS data shows that it identifies important health disparities among communities, most notably those for inner city and suburban communities. The design of the NCHS Urban-Rural Classification Scheme for Counties makes it particularly well-suited for assessing and monitoring health differences across the full urbanization continuum.