DE 3 begins at an intersection with Lighthouse Road/Hay Road at an interchange with I-495 in an industrial section of Edgemoor, heading northwest on four-lane divided Edgemoor Road. After the I-495 interchange, the road passes over Norfolk Southern's Shellpot Secondaryrailroad line and Amtrak's Northeast Corridor railroad line before it intersects US 13 in areas of businesses. Past this intersection, DE 3 enters a more residential area as a three-lane undivided road with two southbound lanes and one northbound lane. The route narrows to two lanes and turns west and north, coming to an intersection with US 13 Bus. At this point, DE 3 turns northeast to form a concurrency with that route on four-lane undivided Philadelphia Pike, running through residential and commercial areas. DE 3 splits from US 13 Bus. at the northwest edge of the town of Bellefonte by turning northwest onto Washington Street Extension, a four-lane divided highway. The route passes to the southwest of Mount Pleasant High School and turns north onto Marsh Road, a four-lane undivided road that forms the western boundary of Bellevue State Park. The road becomes a divided highway as it comes to an interchange with I-95. Immediately after this interchange, DE 3 crosses under CSX's Philadelphia Subdivision railroad line and narrows into a two-lane undivided road that heads into Brandywine Hundred, passing east of a park and ride lot located at a church and running through residential neighborhoods and a few businesses. The route gains a center left-turn lane between Wilson Road/Veale Road and Silverside Road. The road curves northeast and forms the western border of the village of Arden. DE 3 turns north again past the Grubb Road/Harvey Road intersection and runs between neighborhoods to the west and woodland to the east, ending at an intersection with DE 92 in Hanbys Corner. Marsh Road continues north past this intersection as an unnumbered road toward the Pennsylvania border. DE 3 has an annual average daily traffic count ranging from a high of 13,642 vehicles at the I-95 interchange to a low of 4,708 vehicles on Washington Street Extension. None of DE 3 is part of the National Highway System.
History
What is now DE 3 existed as a county road by 1920. Four years later, the road was upgraded to a state highway between Philadelphia Pike and Harvey Road. The state highway was extended north to Naamans Road by 1931. By 1968, DE 3 was designated to run from US 13 north to DE 92 along Marsh Road. DE 4 was extended onto the Washington Street Extension portion of present-day DE 3 three years later. DE 4 was removed from Washington Street Extension by 1981. Three years later, DE 3 was extended to I-495 in Edgemoor. At this time, DE 3 was realigned to follow Washington Street Extension from Marsh Road to a concurrency with US 13 Bus., heading southwest along that route before heading southeast along Edgemoor Road.
