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
Howard County, Maryland Howard County, Maryland Howard County is a county in the central part of the U.S. state of Maryland. As of the 2010 census, the population was 287,085. Its county seat is Ellicott City. Howard County is included in the Baltimore-Columbia-Towson, MD Metropolitan Statistical Area, which is also included in the Washington-Baltimore-Arlington, DC-MD-VA-WV-PA Combined Statistical Area. However, recent development in the south of the county has led to some realignment towards the Washington, D.C. media and employment markets. The county is home to Columbia, a major planned community of approximately 100,000 founded by developer James Rouse in 1967. Howard County is