The Census defines Core Based Statistical Areas as follows:

“Metropolitan and micropolitan statistical areas (metro and micro areas) are geographic entities delineated by the Office of Management and Budget for use by Federal statistical agencies in collecting, tabulating, and publishing Federal statistics. The term “Core Based Statistical Area” (CBSA) is a collective term for both metro and micro areas. A metro area contains a core urban area of 50,000 or more population, and a micro area contains an urban core of at least 10,000 (but less than 50,000) population. Each metro or micro area consists of one or more counties and includes the counties containing the core urban area, as well as any adjacent counties that have a high degree of social and economic integration (as measured by commuting to work) with the urban core.”

When releasing population counts for CBSAs, the Census provides estimates for both the number of people living in the principal city (or cities) of the CBSA, and the number of people living outside the city (cities); some metro areas have more than one principal city. Using these data, I’ve constructed a map that shows the balance between the urban and suburban population for each of these areas. Specifically, the map shows the percentage of people who live in one of the principal cities (urban setting). I have distinguished between metro and micro areas using different outline shades - the lighter shade indicates a metro area and the darker indicates a micro area.

On average, 39.0% of people living in a metro area live within the limits of the principal city. In micro areas, a slightly lower percentage (32.9%) live in the principal city, so there is a slightly higher preference for suburban living in micro areas. Of course, some would consider anyone living in one of these micro areas to be in a suburban setting! Overall, CBSAs in the middle of the country have a more urban-focused population, while coastal CBSAs have a larger proportion of suburban citizens.

Data sources: http://www.census.gov/population/metro/ and http://factfinder2.census.gov/ (Table GCT-P2)