ABCD Counties Definition

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Updated September 29, 2022
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Reviewed by Michelle P. Scott
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Michelle P. Scott is a New York attorney with extensive experience in tax, corporate, financial, and nonprofit law, and public policy. As General Counsel, private practitioner, and Congressional counsel, she has advised financial institutions, businesses, charities, individuals, and public officials, and written and lectured extensively.

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What Are ABCD Counties?

The term ABCD Counties refers to a list of categories of American counties. This list is devised by Nielsen and is based on U.S. Census Bureau population data and metropolitan areas. ABCD Counties are used by entities within the advertising industry, including marketing and advertising agencies, to prepare, execute, and analyze advertising and media plans.

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 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.

Understanding ABCD Counties

A county is a specific region or subdivision of a state. It tends to be defined as a legal administrative and political unit of its state. The U.S. Census Bureau collects and reports data for counties, along with those from cities and states, as well as national statistics on a regular basis. According to the U.S. Census Bureau, there were a total of 3,143 counties as of March 2022.

As noted above, all American counties are categorized as ABCD Counties by Nielsen, which is a corporation that measures information and data. Nielsen is responsible for disseminating information about audiences, consumer goods and behavior, marketing, and media consumption among other things.

ABCD Counties are based on the population totals of U.S. counties and their proximity to a metropolitan area or anchor city. Counties that fall in the A category are the largest by population while D counties are the smallest. Counties are classified on the basis of data from the latest census, which takes place every 10 years. The following is a more detailed description of each category:

  • A County: Any county located in one of the 25 largest U.S. cities that have more than 20,000 households. These 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 area that is not an A County or a B County and has a population of over 40,000. Any area that is classified as a C County has more than 20,000 households or is located in Consolidated Metropolitan Statistical Areas or metropolitan statistical areas (MSAs) that have more than 20,000 households. C Counties account for more than 15% of households in the United States.
  • D County: Any county statistical area that is not designated as an A, B, or C County, so there are 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.

Information derived from the ABCD Counties is used by different entities that operate within the advertising industry. They include marketing and advertising agencies, advertisers, media buyers, and various others. The data collected is used to help these players tailor advertising and media campaigns and plans.

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

Special Considerations

Every one of the counties (or parishes as they're called 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.

The list of ABCD Counties also incorporates the cases in which U.S. cities are not part of a county and therefore stand alone or are independent for census purposes. According to the Census Bureau, there are 41 such cities in Virginia, along with one in Maryland (Baltimore), Missouri (St. Louis), and Nevada (Carson City).

Article Sources
Investopedia requires writers to use primary sources to support their work. These include white papers, government data, original reporting, and interviews with industry experts. We also reference original research from other reputable publishers where appropriate. You can learn more about the standards we follow in producing accurate, unbiased content in our editorial policy.

  1. United States Census Bureau. "COVID-19 pandemic's impact on births and deaths results in a record number of counties experiencing natural decrease."

  2. Nielsen.com. "DMA® Regions."

  3. United States Census Bureau. "Places," Page 9.

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