Delaware Route 4 (DE 4) is a state highway in New Castle County, Delaware. The route runs from DE 279 and DE 896 in Newark east to DE 48 in downtown Wilmington. The route passes through suburban areas in northern New Castle County between Newark and Wilmington, intersecting DE 72 in the eastern part of Newark, DE 273 in Ogletown, DE 58 in Christiana, DE 7 in Stanton, DE 141 in Newport, DE 62 and DE 100 between Newport and Wilmington, and Interstate 95 (I-95)/U.S. Route 202 (US 202) in Wilmington. DE 4 is a four-lane road for much of its length.

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.