Delaware Route 48 (DE 48) is a state highway in New Castle County, Delaware. The route runs from DE 41 in Hockessin east to U.S. Route 13 Business in downtown Wilmington. The route passes through suburban areas of Wilmington along Lancaster Pike, intersecting DE 100 and DE 141. DE 48 continues into Wilmington as Lancaster Avenue and intersects DE 2, where it splits into the one-way pair of Lancaster Avenue eastbound and Second Street westbound. Upon reaching downtown Wilmington, the route intersects Interstate 95 (I-95)/US 202 and DE 4 before continuing to the eastern terminus.

New Castle County is the northernmost of the three counties of the U.S. state of Delaware. As of the 2020 census, the population was 570,719, making it the most populous county in Delaware, with nearly 60% of the state's population of 989,948. The county seat is Wilmington, which is also the state's most populous city.