St. Mary's County is located in the southern part of Maryland, bordered by the Potomac River to the west and the Chesapeake Bay to the east. It is known for its rich history, including the founding of the first permanent English settlement in Maryland in 1634. The county features a mix of rural landscapes, waterfront areas, and small towns. The county seat is Leonardtown, which serves as the cultural and economic center. St. Mary's County is home to several parks, historical sites, and the Patuxent River Naval Air Station, contributing to its diverse community and recreational opportunities.