Delaware Route 1 (DE 1) is the longest numbered state highway in the U.S. state of Delaware. The route runs 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 road 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. In the 1980s, a controlled-access "Relief Route" of US 13 was proposed between Dover and the Wilmington area in order to relieve that route of beach traffic. This proposed highway was incorporated into DE 1 in 1988, with the route extended north concurrent with US 113 between Milford and Dover to connect to the Relief Route. The DE 1 freeway between Dover Air Force Base and Christiana opened in multiple stages between 1991 and 2003, and at a cost of $900 million was the largest public works project in Delaware history. The concurrent US 113 designation between Milford and Dover Air Force Base was removed in 2004. Upgrades continue to be made to DE 1 such as the construction and improvement of interchanges as well as widening portions of the road.
Route description
DE 1 begins at MD 528 at the Maryland state line in Fenwick Island, where it heads north along a multilane divided highway called Coastal Highway through the Delaware Beaches resort area along the Atlantic Ocean, crossing the Indian River Inlet on the Indian River Inlet Bridge. In Dewey Beach, the route turns northwest away from the ocean, running through commercial development from Rehoboth Beach to Nassau. DE 1 forms a concurrency with US 9 from Carpenters Corner to Nassau. Past Nassau, DE 1 leaves the Delaware Beaches resort area and runs northwest through rural areas in northern Sussex County. The route bypasses Milford to the east along the Milford Bypass, crossing into Kent County. After an interchange with the northern terminus of US 113, DE 1 heads north along Bay Road through more rural areas, passing east of Frederica. The route becomes a freeway near Magnolia and turns into a toll road called the Korean War Veterans Memorial Highway while passing Dover Air Force Base. DE 1 bypasses the city of Dover to the east and begins to run parallel to US 13. The route passes east of Smyrna and enters New Castle County, where it crosses US 13 multiple times and heads west of Odessa. The road has an interchange with the northern terminus of the US 301 toll road in Biddles Corner. The toll road portion of the route ends before it crosses the Chesapeake & Delaware Canal on the Senator William V. Roth Jr. Bridge in St. Georges. DE 1 becomes concurrent with US 13 from Wrangle Hill to Tybouts Corner, where US 13 splits to the northeast. The DE 1 freeway heads north and meets US 40 in Bear before it comes to Christiana, where DE 7 joins the route. The DE 1 designation ends at an interchange with I-95 and DE 7 continues north along the freeway to the DE 58 interchange, from which point DE 7 turns into a divided highway with at-grade intersections.