Frederick County

Frederick County is located in Maryland. As of the 2020 U.S. census, the population was 271,717. Frederick is the Capital city of Frederick County and is part of the Washington-Arlington-Alexandria, DC-VA-MD-WV Metropolitan Statistical Area. Like other outlying sections of the Washington metropolitan area, Frederick County has experienced a rapid population increase in recent years. It borders the southern border of Pennsylvania and the northeastern border of Virginia.