The portion of the DuPont Highway between Dover and Wilmington saw increased traffic from connecting interstate roads and summer travelers, prompting the Delaware State Highway Department (DSHD) to consider widening the highway in 1925. A year later, the department suggested the Philadelphia Pike be widened along with the DuPont Highway between State Road and Wilmington. This proposal included widening the bridge over a Pennsylvania Railroad line (now the Jack A. Markell Trail) in Farnhurst that was built in 1902. US 13 was widened to four lanes between State Road and Wilmington and between Shellpot Park and Bellevue Quarry along the Philadelphia Pike in 1927. The same year, the department recommended expanding the road between St. Georges and State Road into a divided highway. In 1928, the widening of Philadelphia Pike was completed. In 1929, the portion of the highway between St. Georges and State Road was widened into a divided highway. The department recommended widening the part of US 13 between Delmar and Dover in 1930 as it was one of the main routes across the Delmarva Peninsula. In addition, plans began to widen the route into a divided highway between Drawyers Creek north of Odessa and St. Georges. The divided highway portion of US 13 between Drawyers Creek and St. Georges was completed in September 1931. Also, work on widening the route to a divided highway between Fieldsboro and Drawyers Creek and from State Road to Wilmington began. The same year, recommendations began to extend the divided highway portion of US 13 south to Dover.