Maryland Route 4 emerges from southeast Washington, DC, bearing the famed name of Pennsylvania Avenue. It winds through the Prince George's County areas of Suitland and Upper Marlboro as a freeway, encountering the Capital Beltway and U.S. Route 301 at interchanges, then pays a short visit to southern Anne Arundel County before serving as the main thoroughfare of Calvert County, and finally crossing the Patuxent River on its way to an end at Maryland Route 5 in Leonardtown, St. Mary's County. Between Sunderland and Solomons in Calvert County, including through the Prince Frederick hub, the route is concurrent with Maryland Route 2.