The main artery serving Calvert County is Maryland Route 4 (which begins in Washington, D.C. as Pennsylvania Avenue before crossing into Prince George's County, Maryland and Anne Arundel County, Maryland). Route 4 in Calvert County begins at the very northern tip of the county at Lyons Creek, approximately 3 miles north of Dunkirk. At Sunderland, Route 4 meets Maryland Route 2 (traveling south as a two-lane road from Annapolis) and the two roads merge as Maryland Route 2-4. Route 2-4 continues south through Prince Frederick, St. Leonard and Lusby. At Solomons, Routes 2 and 4 split again, with Route 2 heading towards downtown Solomons and Route 4 crossing the Patuxent River at the Governor Thomas Johnson Bridge into St. Mary's County.