Delaware Route 72 (DE 72) is a state highway located in New Castle County, Delaware. The route runs from DE 9 near Delaware City north to DE 7 in Pike Creek. The route runs through suburban areas of northern New Castle County, passing through the eastern part of Newark. DE 72 intersects U.S. Route 13 (US 13), DE 1, and DE 7 near Delaware City, DE 71 near Kirkwood, US 40 east of Glasgow, and DE 2, DE 4, and DE 273 in Newark. Parts of DE 72 were built as a state highway during the 1940s. By the 1940s, the route was designated between DE 2 in Newark and DE 7 in Pike Creek along Paper Mill Road. The route was extended south to DE 9 in the 1960s. In 1980, the alignment was shifted to the east through Newark to bypass a railroad crossing on Chapel Street.

DE 72 begins at an intersection with DE 9 adjacent to the Delaware City Refinery near Delaware City, heading west on two-lane undivided Wrangle Hill Road. The road continues between the oil refinery to the north and farmland to the south, continuing through more rural areas before coming to an intersection with US 13 and the southern terminus of DE 7, where it widens into a four-lane divided highway. At this point, US 13 heads west for a short concurrency with DE 72 to a diamond interchange with the DE 1 freeway, where US 13 heads north on DE 1. Past this interchange, DE 72 narrows back into a two-lane undivided road and passes through a mix of farmland and residences, coming to an intersection with DE 71. Following this, the road curves to the northwest through a mix of homes and commercial establishments, crossing Norfolk Southern's Delmarva Secondary railroad line. The route continues through more areas of suburban residential development and curves to the north, coming to an intersection with US 40 in a commercial area to the east of Glasgow.

Past the US 40 intersection, DE 72 continues to the north on Sunset Lake Road, heading into wooded areas and closely running to the west of a Norfolk Southern line. The road continues north-northwest through woodland with some fields and residential development. The route crosses to the east side of the railroad tracks and widens into a five-lane road with a center left-turn lane as it comes to an intersection with Old Baltimore Pike. At this intersection, the route name changes to South Chapel Street and it passes through fields and development, crossing under Interstate 95 (I-95, Delaware Turnpike) without an interchange. DE 72 heads into the eastern part of Newark and passes industrial parks before heading between commercial development to the west and residential neighborhoods to the east as it comes to an intersection with DE 2/DE 4.

At this point, DE 2 turns north to form a concurrency with DE 72, with the road narrowing to two lanes as it heads through agricultural areas to the east of the University of Delaware campus. The two routes continue northeast onto Library Avenue and heads through woods as it comes to a bridge over Amtrak's Northeast Corridor railroad line. The road heads north into commercial areas and widens into a four-lane divided highway as it comes to an intersection with Delaware Avenue, which carries the eastbound direction of DE 2 Bus./DE 273. Here, eastbound DE 273 turns north to join DE 2/DE 72 and the road reaches an intersection where westbound DE 2 Bus./DE 273 head west on Main Street and DE 273 continues east as Ogletown Road. Past this intersection, the name of DE 2/DE 72 becomes Capitol Trail as it turns northeast and passes under CSX's Philadelphia Subdivision railroad line. The road leaves Newark and continues northeast through wooded residential areas, briefly becoming undivided as it crosses White Clay Creek.

DE 72 splits from DE 2 by heading northwest on two-lane undivided Possum Park Road, heading through wooded areas with some fields and neighborhoods. In Milford Crossroads, the route turns northeast onto Paper Mill Road and continues through fields and woods, curving north and passing between White Clay Creek State Park to the west and the Middle Run Valley Natural Area to the east. The road heads northeast into suburban neighborhoods of the Pike Creek area. DE 72 turns east and reaches its northern terminus at another intersection with DE 7.

DE 72 has an annual average daily traffic count ranging from a high of 34,091 vehicles at the north end of Newark to a low of 3,489 vehicles at the US 13 intersection. The brief portion of DE 72 concurrent with US 13 is part of the National Highway System.

What is now DE 72 originally existed as a county road by 1920. By 1931, the road was proposed as a state highway between present-day DE 9 and US 13 while what would become DE 72 north of Milford Crossroads was completed as a state highway. The road from present-day DE 9 and US 13 became a state highway by 1932. When Delaware first assigned state route numbers by 1936, the state highway was built between US 13 and US 40 was finished. At this time, the road was not assigned a route number. By 1938, the road between Newark and Milford Crossroads became a state highway. DE 72 was designated by 1942 to run from DE 2 in Newark north to DE 7, following Chapel Street and Paper Mill Road. The route was extended to its present southern terminus at DE 9 by 1967, following Chapel Street, Sunset Lake Road, and Wrangle Hill Road. In 1980, the Chapel Street crossing of the Northeast Corridor rail line in Newark was permanently blocked, and DE 72 was realigned farther to the east to follow Library Avenue across the railroad tracks before continuing north on DE 2 and Possum Park Road to Paper Mill Road in Milford Crossroads. DE 2 was realigned to follow DE 72 around the eastern part of Newark on Library Avenue by 1990.

The entire route is in New Castle County.