The Delaware General Assembly created the DSHD in 1917 to lay out, construct, and maintain highways and to meet organizational requirements to receive federal aid through the Federal Aid Road Act of 1916. On July 20, 1918, DuPont reached an agreement with the state of Delaware for the newly formed DSHD to construct the remaining sections of the highway. DuPont would dissolve Coleman DuPont Road, Inc., and finance the remainder of construction up to , which is equivalent to in . The highway department would complete the road to Milford along the lines designed by DuPont's company. DSHD would both design and construct the DuPont Highway north of Milford; the department decided on a right-of-way for future sections of the highway. The portions from north of Ellendale to north of Milford, from Frederica to Little Heaven, and through Rising Sun were completed by 1920. All other portions of the DuPont Highway between Ellendale and Dover were under construction in 1920 and completed by 1923, the same year the last section of the entire Selbyville–Wilmington highway was completed near Odessa.