Washington County, Maryland Washington County, Maryland Washington County is located in the western part of the U.S. state of Maryland. As of the 2010 census, the population was 147,430. Its county seat is Hagerstown. Washington County was the first county in the United States to be named for the Revolutionary War general (and later President) George Washington. Washington County is one of three Maryland counties recognized by the Appalachian Regional Commission as being part of Appalachia. The county borders southern Pennsylvania to the north, Northern Virginia to the south, and the Eastern Panhandle of West Virginia to the south and west. Washington County
Montgomery County, Maryland Montgomery County, Maryland Montgomery County is the most populous county in the U.S. state of Maryland, located adjacent to Washington, D.C. As of the 2010 census, the county's population was 971,777, increasing by 9.0% to an estimated 1,058,810 in 2017. The county seat and largest municipality is Rockville, although the census-designated place of Germantown is the most populous place. Montgomery County is included in the Washington–Arlington–Alexandria, DC–VA–MD–WV Metropolitan Statistical Area, which in turn forms part of the Baltimore–Washington Combined Statistical Area. Most of the county's residents live in unincorporated locales, of which the most built up are Silver Spring and