Frederick County Real Estate View 440 listings HomeGuidesFrederick County “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.[3][4] 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. Notable persons from here include Francis Scott Key, Chris Rose, Zach Taylor, Matt Bennett, Thomas Johnson, Roger B. Taney, and Barbara Fritchie.” Learn More Guides Anne Arundel CountyBaltimore CityBaltimore CountyCarroll CountyFrederick CountyHarford CountyHoward CountyMontgomery CountyPrince Georges County