What Are ABCD Counties?

ABCD Counties are categories of U.S. counties devised by The Nielsen Corp. based on U.S. Census Bureau population data and metropolitan areas. Such county classifications are used by marketing and advertising agencies, advertisers, media buyers and various other entities in the preparation, execution, and analysis of advertising and media plans.

ABCD Counties are based on the population totals of U.S. counties and also their proximity to a metro area or anchor city. A counties are the largest U.S. counties by population, and D counties are the smallest. Counties are classified on the basis of data from the latest census, which takes place every 10 years.

Key Takeaways

  • ABCD Counties are the way different counties in the U.S. are classified based on population size.
  • The population size is based on census data gathered by the U.S. Census, looking at county size on a ten-year basis.
  • The system was devised by the Nielsen Corp. and intended to be used broadly in advertising and media.
  • A Counties come from the 25 largest U.S. cities and have more than 20,000 households, while D Counties are very rural and have no population requirements.
  • B and C Counties fall in-between A and D Counties in terms of size and population.

Breaking Down ABCD Counties

Every one of the 3,142 counties, parishes (as in Louisiana), and organized and unorganized boroughs (as in Alaska) in the United States gets a single designation based on data from the most recent census. It also incorporates the several cases in which U.S. cities are not part of a county and therefore stand alone for census purposes (there are 38 such cities in the Commonwealth of Virginia, and one each in Maryland, Nevada, and Missouri). They are:

  • A County: Any county located in one of the 25 largest U.S. cities that have more than 20,000 households. A Counties represent highly urbanized areas and account for more than 40% of households in the United States.
  • B County: Any county that does not qualify as an A County, which also has a population of at least 150,000, or is part of a consolidated statistical area with a population over 150,000. B Counties have at least 85,000 households, and when combined, account for about 30% of all U.S. households.
  • C County: Any county or consolidated statistical areas that is not an A County or a B County and has a population over 40,000. A C County has more than 20,000 households or is located in Consolidated Metropolitan Statistical Areas or Metropolitan Statistical Areas that have more than 20,000 households. C Counties account for more than 15% of the households in the United States.
  • D County: Any county statistical area that is not designated as an A, B or C County (no limits placed on population). D Counties are considered very rural and are generally far from any sizable population center. When combined, D Counties account for roughly 15% of all U.S. households.

The ABCD county categorization system differs from Nielsen's DMA (Designated Market Area) system of measuring television viewing.