After DE 9A, DE 9 enters the city of Wilmington and heads through urban areas as an undivided road, crossing Norfolk Southern's Shellpot Secondary at-grade before intersecting the northbound direction of US 13. At this point, DE 9 splits into a one-way pair with the northbound direction becoming concurrent with northbound US 13 on one-way New Castle Avenue and the southbound direction following southbound US 13 on South Heald Street, briefly turning east along with northbound US 13 on D Street at the south end of the one-way pair. The one-way pair, which carries two lanes in each direction, passes rowhomes and businesses, with New Castle Avenue merging onto South Heald Street. Here, US 13/DE 9 continue north-northeast on four-lane undivided South Heald Street, coming to an intersection with the northern terminus of DE 9A.