The list contains the largest contiguous public parks-preserves within 30 miles (48 km) of either Baltimore, Maryland or Washington, D.C., which is within the Baltimore–Washington metropolitan area. 1. * Prince William Forest - Locust Shade, Virginia; 18,255 acres (74 km2) — about one-third is closed to the public 2. * Patuxent Wildlife Research Refuge - Fran Uhler (Patuxent River Park), Maryland; 13,300 acres (54 km2) — about one-third is closed to the public 3. * Seneca Creek - McKee-Beshers - C & O Canal - Germantown, Maryland / Algonkian, Virginia; 12,435 acres (50 km2) 4. * Upper Patapsco, Maryland; 9,575 acres (39 km2) 5. * Patuxent River Park - Merkle - Jug Bay Wetlands - House Creek, Maryland; 8,759 acres (35 km2) 6. * Mason Neck - Accotink Bay - Pohick - Meadowwood - G