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
Streets and highways of Washington, D.C. frequently used to describe the inside lanes of 495—that is, those that travel clockwise around Washington. A convergence indexing based road traffic monitoring system was installed on Washington's highways in 2008. The Anacostia Freeway (DC-295) continues in a northeasterly direction from the point where I-295 ends at its intersection with I-695 near the 11th Street Bridges on the south side of the Anacostia River and links with the Baltimore–Washington Parkway, which eventually becomes Maryland Route 295, via a short section of Maryland Route 201. The Suitland Parkway connects the city with the southeastern suburbs in Prince George's County, Maryland. The