Calvert County is a county located in the U.S. state of Maryland. As of the 2010 census, the population was 88,737. Its county seat is Prince Frederick. The county's name is derived from the family name of the Barons of Baltimore, the proprietors of the English Colony of Maryland.
Calvert County is included in the is included in the Washington-Arlington-Alexandria, DC-VA-MD-WV Metropolitan Statistical Area. It occupies the Calvert Peninsula, which is bordered on the east by Chesapeake Bay and on the west by the Patuxent River.
Calvert County is part of the Southern Maryland region. The county has one of the highest median household incomes in the United States.
First settled as part of Charles County (much larger than the present-day Charles County) around 1650, it was renamed. Patuxent County was established in 1654 by an Order in Council. In 1658 the county was renamed Calvert County. It is one of the older counties in Maryland, after St. Mary's County, Kent County and Anne Arundel County.
Once made up primarily of farms and tobacco fields, the county has become a fast-growing exurban neighbor of Washington. Many home prices have nearly quadrupled in the past decade, with many four-bedroom homes in the northern half of the county averaging over $1,000,000. The popular weekend resort towns of Solomons, Chesapeake Beach, and North Beach are notable.
The county has a number of properties on the National Register of Historic Places.