List of the most populous counties in the United States
This is a list of the 100 most populous counties in the United States based on the national decennial US census conducted on April 1, 2010 and subsequent mid-2010 and mid-2019 official estimates released by the United States Census Bureau (USCB).
Many of the counties on the list include major cities or metropolitan areas in all parts of the United States. Six of the listed counties have consolidated city and county government, namely the City and County of Honolulu, Metropolitan Government of Nashville and Davidson County, Tennessee, City and County of Philadelphia, City and County of San Francisco, City of Jacksonville and Duval County and City and County of Denver. New York County, Bronx County, Kings County, Queens County, and Richmond County, are coterminous with the respective boroughs of New York City, and fall under the jurisdiction of the combined city government.
This list lists the most populous US counties and the District of Columbia sorted according to the mid-2018 official estimate by the United States Census Bureau (USCB).
Aerial view of Orange County, California, the sixth-most populous county in the United States.