Delaware Route 1

Delaware Route 1 (DE 1) is the longest numbered state highway in the U.S. state of Delaware. The route runs 102.63 mi (165.17 km) from the Maryland state line in Fenwick Island, Sussex County, where the road continues south into that state as Maryland Route 528 (MD 528), north to an interchange with Interstate 95 (I-95) in Christiana, New Castle County, where the roadway continues north as part of DE 7. Between Fenwick Island and Dover Air Force Base in Dover, Kent County, DE 1 is a multilane divided highway with at-grade intersections and occasional interchanges. The route heads north through the Delaware Beaches resort area along the Atlantic Ocean before it runs northwest through rural areas, turning north at Milford to continue to Dover. Upon reaching Dover, DE 1 becomes the Korean War Veterans Memorial Highway, a freeway that is partially tolled. Between Dover and Tybouts Corner, DE 1 parallels U.S. Route 13 (US 13), crossing over and featuring interchanges with it multiple times. Past Tybouts Corner, the freeway heads north parallel to DE 7 to the northern terminus of DE 1 in Christiana. DE 1 serves as the main north-south state highway in Delaware, connecting the Delaware Beaches with the Dover and Wilmington areas.

DE 1 was first designated in the 1970s from Fenwick Island north to US 113 in Milford, replacing a portion of DE 14 south of Milford and following the newly-constructed Milford Bypass. DE 14 between Fenwick Island and Milford had been built as a state highway in the 1920s and 1930s and was widened into a divided highway between the 1950s and 1970s.