Delaware Route 4 (DE 4) is a state highway in New Castle County, Delaware. The route runs from DE 2 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 much of its length.

What is now DE 4 was originally a county road that was paved in the 1930s. DE 4 was designated in the 1960s to run from the Maryland border along Chestnut Hill Road near Newark east to DE 48 in Wilmington. Between 1971 and 1981, the route extended past DE 48 along Washington Street and Washington Street Extension to US 13 Business (US 13 Bus.) in Bellefonte. In the 1980s, the western terminus of DE 4 was realigned from Chestnut Hill Road to the newly-built Christiana Parkway, terminating at DE 2 and DE 896.

DE 4 begins at an intersection with Elkton Road in Newark, which heads southwest as DE 2 and northeast as DE 2 Bus./DE 896. From here the route heads southeast concurrent with DE 2 and DE 896 on the three-lane undivided Christiana Parkway, carrying two eastbound lanes and one westbound lane. The road runs through wooded areas and comes to a bridge over Amtrak's Northeast Corridor railroad line, curving east and widening into a four-lane divided highway as it passes to the south of the former Newark Assembly plant used by Chrysler. At the intersection with South College Avenue DE 896 splits to the south and DE 2/DE 4 continues east past the University of Delaware campus to the north, intersecting Chestnut Hill Road. At this point the road becomes Chestnut Hill Road and runs between farmland to the north and residential neighborhoods to the south, coming to a crossing of Norfolk Southern's Delmarva Secondary railroad line. The road heads into commercial areas and intersects DE 72, where DE 2 splits from DE 4 by heading north along DE 72.

Past this intersection DE 4 continues east along Chestnut Hill Road and heads into suburban Brookside, passing through residential neighborhoods with some businesses and curving to the northeast. The route continues to Ogletown where it has an interchange with DE 273 and the name changes to Ogletown Stanton Road. Following this the road heads through more residential and commercial areas, passing to the north of Christiana Hospital. Beyond the hospital DE 4 comes to an intersection with the western terminus of DE 58 in Christiana. The route continues through commercial areas with some woods, curving east and coming to an intersection with DE 7.

At this point DE 4 turns north for a concurrency with DE 7 on the six-lane divided Stanton Christiana Road, passing through wooded areas with nearby development and passing over Amtrak's Northeast Corridor and White Clay Creek. The road passes to the east of Delaware Park Racetrack and curves northeast, heading into Stanton. At this point the two routes head into a commercial area and split into the one-way pair of Mitch Road eastbound and Main Street westbound. DE 7 splits from DE 4 by heading northwest on Limestone Road. DE 4 continues east along the one-way pair past homes and businesses, carrying two lanes in each direction. The directions of the route rejoin and the route becomes four-lane divided West Newport Pike, running through a mix of suburban neighborhoods and commercial establishments. DE 4 enters Newport and splits into the one-way pair of West Market Street eastbound and West Justis Street westbound, passing homes along with some businesses. The route interchanges with the DE 141, with the one-way pair becoming East Market Street eastbound and East Justis Street westbound.

The two directions of DE 4 rejoin and the route continues northeast as four-lane undivided East Newport Pike, leaving Newport and heading between suburban neighborhoods to the northwest and Banning Park to the southeast. The route intersects DE 62 and becomes Maryland Avenue, passing a mix of homes and businesses. The road comes to an intersection with the southern terminus of DE 100 and runs through more developed areas, crossing a CSX railroad line. DE 4 continues into Wilmington and passes through urban areas of rowhomes and businesses. The route passes under I-95/US 202 and comes to a ramp from northbound I-95/US 202. Past this DE 4 enters downtown Wilmington and splits into the one-way pair of Maryland Avenue eastbound and South Monroe Street westbound before ending at DE 48, which is routed on the one-way pair of Martin Luther King Jr. Boulevard eastbound and West Second Street westbound.

DE 4 has an annual average daily traffic count ranging from a high of 53,936 vehicles at the west end of the DE 7 concurrency to a low of 12,033 vehicles at the I-95/US 202 interchange. The portions of DE 4 concurrent with DE 7 and between I-95/US 202 and DE 48 are part of the National Highway System.

By 1920 what would become DE 4 existed as a county road. The road from Stanton to Wilmington was paved by 1924 and the portion west of Stanton was paved by 1936. The present DE 4 designation first appeared in 1967, at which point it ran from the Maryland border near Newark east to DE 48 in Wilmington, following Chestnut Hill Road from the state line before picking up its current alignment southeast of Newark. By 1971 the route was extended northeast to US 13 Bus. in Bellefonte, forming a brief concurrency with DE 48 before continuing along Washington Street and Washington Street Extension. DE 4 was truncated back to DE 48 by 1981, with DE 3 being realigned to the easternmost part of Washington Street Extension by 1984. The Christiana Parkway around the southern edge of Newark was completed by 1984 and DE 4 was realigned to use the Christiana Parkway by 1987, ending at DE 2 in the southwestern part of Newark. DE 896 was rerouted to use the Christiana Parkway by 1988 with DE 2 following by 1990.

The entire route is in New Castle County.