St. Mary's County itself, the southernmost of the three counties, has 400 miles of shoreline on the Potomac, the Patuxent River, and the Bay, as well as along countless creeks and inlets. The College is located near the tip of the Southern Maryland peninsula, along the St. Mary's River, a short distance from the Potomac River and its confluence with the Chesapeake Bay. The county is largely rural, with broad stretches of farmland and forest. Agriculture and the seafood industry have always figured prominently in the local economy. Farmers continue to grow tobacco, a vital cash crop since colonial times, as well as corn and soybeans.
Watermen still harvest oysters in the cooler months, blue crabs and fish in the summer.
Wildlife is plentiful in the region. Wild swans, ducks, and Canada geese winter the creeks and ponds of the county every year. County life retains a rural flavor and many rural customs. But major economic and social changes are underway in the area as a result of dynamic growth in the local defense industry. The center of this industry and the driving economic force in the county today is the Patuxent Naval Air Warfare Center, which tests Naval warplanes and related technical equipment before they are accepted for use by the military.