Some large bridges in the state are maintained by other agencies including the U.S. Army Corps of Engineers and the Delaware River and Bay Authority.

The creation of the Interstate Highway System in 1956 led to the construction of 40 miles (64 km) of freeway in northern New Castle County, including the tolled Delaware Turnpike.

The Delaware Route 1 (DE 1) limited-access toll road between Dover and Wilmington was fully completed in 2003, and was the largest public works project in state history.

[6][23] Delaware has a total of 40.61 miles (65.36 km) of freeway considered part of the Interstate Highway System.

[6] A mainline toll plaza is located along the Delaware Turnpike portion of I-95 near the Maryland border in Newark.

The Transportation Trust Fund receives revenue from tolls along I-95 and DE 1, motor fuel taxes of 23 cents per gallon on gasoline and 22 cents per gallon on special fuels, motor vehicle document and registration fees, and DMV fees.

[23] The Delaware Byways system designates state roads that have scenic, historic, natural, cultural, recreational, or archaeological qualities.

[32] The Native Americans who originally inhabited Delaware used waterways to travel, with land trails connecting different bodies of water.

[1] The early roads that existed following Swedish settlement were short and discontinuous and followed Native American trails and animal paths.

Most of the colonial roads im Delaware ran east–west, connecting coastal ports to inland areas.

By the later part of that century, a post road ran from Horn Town, Virginia north across the Delmarva Peninsula towards Philadelphia.

[34] During the course of the 18th century, the road network in Delaware became more developed and provided links to waterways, which were still the primary mode of transportation at the time.

Many other turnpikes were constructed in northern New Castle County radiating from Wilmington and connected the industrial city to agricultural areas.

[1] In 1908, Thomas Coleman DuPont proposed a modern road that was to run the length of the state from Selbyville north to Wilmington as part of a philanthropic measure.

This roadway was planned to improve travel and bring economic development to Kent and Sussex counties.

[1] The DuPont Highway would end up being built as a two-lane concrete road on a 60-foot (18 m) alignment with a 32-foot (9.8 m) wide roadway.

[37] The DuPont Highway was a boon to southern Delaware, which had formerly been economically isolated from the large cities of the northeast.

Southern Delaware also developed into a major truck farming region due to having much greater access to urban markets.

No longer fully reliant on the railroads to transport their goods, farmers in Sussex and Kent counties could market their fruits, vegetables, and broiler chickens directly to consumers in the north.

[1] The first numbered routes in Delaware were announced in 1925 with the creation of the U.S. Highway System, in which US 13, US 40, and US 113 were planned to run through the state.

[40][41] In 1930 and again in 1932, the DSHD recommended giving numbers to state roads to supplement the existing U.S. Highway System.

[2] By 1955, the shield was modified to a square with "DELAWARE" on top and the route number on bottom in FHWA Series font.

In 1935, the DSHD took over maintenance of all remaining county roads, tripling the mileage of the state highway system, and took over several city streets in Wilmington in 1936.

[52][53] The portion of I-95 between the Maryland border near Newark and Newport and I-295 between Newport and the approach to the Delaware Memorial Bridge in Farnhurst was to be built as a free Interstate Highway using federal funds, but was built as the tolled Delaware Turnpike instead in order to speed up construction.

[55] The Delaware Turnpike allowed motorists to travel from Washington, D.C. to Boston without having to stop at a traffic light.

[58] In the 1980s, plans were made for a limited-access Relief Route of US 13 between Dover and the Wilmington area that would alleviate it of traffic heading to the Delaware Beaches in the summer.

The DE 1 toll road between Dover Air Force Base and Christiana opened in stages between 1991 and 2003.

[59] The total cost to build the DE 1 toll road was $900 million and it was the largest public works project in Delaware history.

[62] The most recent proposal called for US 301 to be built as a limited-access toll road from the Maryland border southwest of Middletown northeast to DE 1 in St. Georges.

[63][64][65] DelDOT began a program to pave the last of the state-maintained dirt roads within Delaware in the mid 1990s, which at the time totaled 100 miles (160 km).