Frederick County, Maryland Frederick County, Maryland Frederick County is located in the northern part of the U.S. state of Maryland. As of the 2010 U.S. Census, the population was 240,336. The county seat is Frederick. Frederick County is included in 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. The county is home to Catoctin Mountain Park (encompassing the presidential retreat Camp David) and to the U.S. Army's Fort Detrick. It has also
Washington County, Maryland age 18 and 9.50% of those age 65 or over. According to the Maryland Department of Business and Economic Development, the following were the major employers in the county (excluding post offices, state government, and local governments, but including public institutions of higher education): Washington County Public Schools administers public schools in the county. See "Washington County Public Schools – School Directory" for a detailed listing of elementary, middle, high, and other schools. Public high schools Private high schools Washington County, Maryland Washington County is located in the western part of the U.S. state of Maryland. As of the 2010