 DE 20 was designated to run from the Maryland border in Reliance east to US 113 in Millsboro by 1936 , following its current alignment to Seaford before heading south along what was then US 13 ( Front Street ) to Blades , where it turned east onto High Street and picked up its current alignment to Millsboro . In 1939 , plans were made to eliminate the grade crossing with the Pennsylvania Railroad ( now Norfolk Southern 's Delmarva Secondary ) in Seaford by replacing it with a bridge over the tracks . Construction on this bridge began a year later . On September 2 , 1941 , the DE 20 bridge over the railroad tracks in Seaford opened to traffic . 
