Charles County is a county located in the U.S. state of Maryland. As of the 2020 census, the population was 166,617. The county seat is La Plata. The county was named for Charles Calvert (1637–1715), third Baron Baltimore. Charles County is part of the Washington metropolitan area and the Southern Maryland region.

The Washington metropolitan area, also referred to as the DC area, Greater Washington, the National Capital Region, or locally as the DMV, is the metropolitan area centered around Washington, D.C., the federal capital of the United States. The metropolitan area includes all of Washington, D.C. and parts of Maryland, Virginia, and West Virginia. It is part of the larger Washington–Baltimore combined statistical area, which is the third-largest combined statistical area in the country.