U.S. Route 13 (US 13) is a U.S. highway running from Fayetteville, North Carolina, north to Morrisville, Pennsylvania. In the U.S. state of Delaware, the route runs for . It traverses the entire north–south length of the state from the Maryland state line in Delmar, Sussex County, north to the Pennsylvania state line in Claymont, New Castle County. US 13 connects many important cities and towns in Delaware, including Seaford, Dover, and Wilmington. The entire length of US 13 in Delaware is a multilane divided highway with the exceptions of the segment through Wilmington and parts of the route in Claymont. Between the Maryland state line and Dover, US 13 serves as one of the main north–south routes across the Delmarva Peninsula. From Dover north to Tybouts Corner, the route is followed by the controlled-access Delaware Route 1 (DE 1) toll road, which crosses the route multiple times and has multiple interchanges with it. US 13 bypasses downtown Wilmington to the east before it heads northeast of the city parallel to Interstate 495 (I-495) and the Delaware River to Claymont. US 13 is the longest numbered highway in the state of Delaware.
The portion of US 13 between Delmar and Dover was constructed as a state highway during the 1920s. Between Dover and Wilmington, the route was built as part of the cross-state DuPont Highway, which was completed in 1923 and improved transportation between northern and southern Delaware. North of Wilmington, what would become US 13 was originally built as the Philadelphia Pike in the 1820s and improved to a state highway by 1920. US 13 was designated through Delaware when the U.S. Highway System was created in 1926. The route was widened into a divided highway between Dover and Wilmington in the 1930s and between Delmar and Dover in the 1950s. US 13 was routed to bypass Dover in the 1950s. In 1970, US 13 was moved to its current alignment between Wilmington and Claymont on a bypass built in the 1930s. The portion of US 13 between Dover and Wilmington saw heavy traffic heading to the Delaware Beaches in the summer, which led to the construction of a freeway "Relief Route" parallel to US 13. This freeway was built as DE 1, which was completed in 2003. The construction of DE 1 necessitated the realignment of US 13 in two places.
Route description US 13 enters Delaware from Maryland in Delmar and heads north through Sussex County as a multilane divided highway called Sussex Highway, passing through rural areas and various cities and towns including Laurel, Seaford, Bridgeville, and Greenwood. The route continues into Kent County, where it becomes Dupont Highway and runs north through Harrington, Felton, and Camden. US 13 passes through Dover, where it heads through commercial areas. Past Dover, the route is paralleled by the controlled-access DE 1 toll road and comes to Smyrna, where it enters New Castle County. Here, US 13 continues north and crosses DE 1 multiple times, passing through Odessa. The route crosses the Chesapeake & Delaware Canal on the St. Georges Bridge before it runs concurrent with the DE 1 freeway between Wrangle Hill and Tybouts Corner. Upon splitting from DE 1, US 13 heads northeast through suburban areas along the multilane divided Dupont Highway, forming a concurrency with US 40 in the New Castle area. The route passes through the eastern part of Wilmington on city streets, including a one-way pair. Upon leaving Wilmington, US 13 becomes a multilane divided highway called Governor Printz Boulevard and runs northeast parallel to I-495 and the Delaware River to Claymont, where it follows Philadelphia Pike to the Pennsylvania state line.
The section of US 13 south of Tybouts Corner serves as part of a primary hurricane evacuation route from coastal areas of the Delmarva Peninsula to inland areas to the north. Portions of US 13 in Delaware are designated as part of the Delaware Byways system. The segments between US 13 Alt. (North State Street) in Dover and Main Street in Smyrna, DE 9 (New Castle Avenue) and A Street in Wilmington, and Swedes Landing Road and DE 9 (4th Street) in Wilmington are part of the Harriet Tubman Underground Railroad Byway. The section of US 13 in Delaware between US 13 Bus. (Philadelphia Pike) and the Pennsylvania state line in Claymont is part of the Washington–Rochambeau Revolutionary Route, a National Historic Trail. US 13 in Delaware has an annual average daily traffic count ranging from a high of 77,363 vehicles at the US 202/DE 141 interchange near New Castle to a low of 4,096 vehicles at the southern border of Wilmington. US 13 in Delaware is a part of the National Highway System between the Maryland state line in Delmar and the Puncheon Run Connector freeway in Dover, from DE 1 in Wrangle Hill to I-495 in Minquadale, and between DE 92 and the Pennsylvania state line in Claymont. US 13 in Delaware is designated as a Blue Star Memorial Highway honoring those who have served in the United States Armed Forces; Blue Star Memorial Highway markers are located at the Smyrna Rest Area and in Seaford. The route was designated as a Blue Star Memorial Highway between the Maryland state line and Dover in 1981 and between Dover and the Pennsylvania state line in 1998.
Sussex County
US 13 enters Delaware from Maryland in the town of Delmar in Sussex County. At the state line, the route intersects DE/MD 54, which follows the state line for several miles. US 13 continues north from the DE/MD 54 intersection on four-lane divided Sussex Highway, passing businesses. The route leaves Delmar and heads to the east of US 13 Dragway and Delaware International Speedway, running through wooded areas with some farm fields and development. The road crosses Dorothy Road/Whitesville Road at a superstreet intersection and continues through a mix of farmland and woodland before it reaches the town of Laurel. Here, US 13 heads past a few businesses and comes to a junction with DE 24. Following this, the route crosses Records Pond along Broad Creek and curves northwest. The road passes farm fields before it intersects the western terminus of US 9 and Georgetown Road near businesses. Past this intersection, US 13 leaves Laurel and runs through farms and woods with occasional development. The route heads north again and comes to a junction with DE 20 to the east of the town of Blades, at which point DE 20 turns north for a concurrency with US 13. The road crosses the Nanticoke River and heads into Seaford, where it passes businesses prior to heading across Williams Pond along Clear Brook. Past this, DE 20 splits from US 13 by heading to the west, while US 13 continues north through commercial areas.
US 13 leaves Seaford and continues into rural areas with some development along the road. The road crosses Clear Brook east of Hearns Pond and the highway passes to the east of a residential development as Bridgeville Highway intersects the road. The road passes west of a park and ride lot located at a church and continues near housing subdivisions and businesses before it comes to the DE 18 junction east of Cannon. US 13 heads north past more farmland before it reaches an intersection south of the town of Bridgeville where DE 404 heads to the southeast and US 13 Bus./DE 404 Bus. head northwest into Bridgeville. At this point, US 13 becomes concurrent with DE 404 and the two routes pass through rural areas with some development to the east of Bridgeville. North of town, the road crosses Redden Road before meeting the northern terminus of US 13 Bus. at a southbound right-in/right-out intersection. A short distance later, DE 404 splits from US 13 by heading to the west. From here, the highway runs through a mix of farms and woods with some homes and businesses along the road. Upon reaching the town of Greenwood, the travel lanes of US 13 split to include businesses in the median. In Greenwood, the route crosses DE 16/DE 36. Upon departing Greenwood, the median narrows and the road heads back into rural areas.
Kent County US 13 continues north into Kent County, where the name of the road changes to South Dupont Highway. The route runs through a mix of woodland and farmland with some homes, crossing Booth Branch and passing to the east of the small town of Farmington, with Main Street providing access to the town. To the south of Harrington, US 13 intersects DE 14 Truck and becomes concurrent with that route. The road heads into Harrington and runs through commercial areas, passing to the east of the Delaware State Fairgrounds, which is where the Delaware State Fair is held and the Harrington Raceway & Casino and Centre Ice Rink are located. US 13/DE 14 Truck crosses the Delmarva Central Railroad's Indian River Subdivision line at-grade, with the median widening to include businesses in it. US 13 intersects DE 14, where the concurrent truck route ends, and continues near more commercial establishments before the median narrows again. The route leaves Harrington, where it passes east of a park and ride lot at the Harrington Moose Lodge at the Carpenter Bridge Road intersection, and traverses more farmland before crossing the Murderkill River in a wooded area to the west of Killens Pond State Park. Access to the state park from US 13 is provided by Paradise Alley Road south of the river and Killens Pond Road north of the river. US 13 heads past more farms and some development before it reaches the town of Felton, where it intersects DE 12 and runs near homes and businesses on the eastern edge of the town. After heading out of Felton, the highway passes through rural areas of development before crossing Hudson Branch and coming to Canterbury. Here, the route intersects Evens Road/Irish Hill Road, with Evens Road leading west to the town of Viola. A park and ride lot at a gas station is located on the southeast corner of the intersection. A short distance later, US 13 comes to a junction with DE 15 and forms a short concurrency with that route before DE 15 splits to the northwest along with US 13 Alt. The road traverses woodland before it reaches an intersection with DE 10 Alt. near a few businesses on the eastern edge of the town of Woodside.