The following is a list of numbered routes in Delaware, consisting of Interstate Highways, U.S. Routes, and state routes. The Delaware Department of Transportation is responsible for maintaining numbered roads in Delaware. State routes in Delaware use the circular highway shield. Delaware's numbering system mirrors that of U.S. Highways in that odd numbered highways travel north-south and even numbered routes go east-west. The numbers increase in value as one goes south and west respectively. There are some exceptions, however, mainly with routes from other states keeping their number as they enter Delaware, hence breaking the pattern.
The first numbered routes in Delaware came in 1925 with the designation of the U.S. Highway System, in which US 13, US 40, and US 113 were legislated to run through the state.[1] In 1930 and again in 1932, the Delaware State Highway Department recommended giving numbers to state roads to supplement the existing U.S. Highway System.[2][3] By 1936, Delaware began assigning numbers to state routes.[4] In 1956, the Interstate Highway System was created, with under 40 miles of Interstate highway legislated in New Castle County.[5]
^Special Committee on U.S. Route Numbering (November 14, 1980). "Route Numbering Committee Agenda"(PDF) (Report). Washington, DC: American Association of State Highway and Transportation Officials. p. 519. Retrieved November 13, 2014 – via Wikimedia Commons.
^ Jump up to: abU.S. Route Numbering Subcommittee (June 25, 1974). "U.S. Route Numbering Subcommittee Agenda" (Report). Washington, DC: American Association of State Highway and Transportation Officials. p. 448. Retrieved October 16, 2014 – via Wikisource.
^ Jump up to: abcDelaware Department of Highways and Transportation (1976). Delaware Highways Official Map(PDF) (Map). Dover: Delaware Department of Highways and Transportation. Retrieved November 24, 2015.
^ Jump up to: abSpecial Committee on U.S. Route Numbering (June 20, 1983). "Route Numbering Committee Agenda"(PDF) (Report). Washington, DC: American Association of State Highway and Transportation Officials. p. 535. Retrieved October 11, 2014 – via Wikimedia Commons.
^ Jump up to: abDelaware Department of Transportation (1984). Official State Highway Map(PDF) (Map). Dover: Delaware Department of Transportation. Retrieved November 24, 2015.
^Special Committee on U.S. Route Numbering (October 1, 1983). "Route Numbering Committee Agenda" (Report). Washington, DC: American Association of State Highway and Transportation Officials. p. 538. Retrieved October 15, 2014 – via Wikisource.
^ Jump up to: abDelaware Department of Transportation Division of Planning Cartographic Information Section (1996). Delaware Official State Map(PDF) (Map). Dover: Delaware Department of Transportation. Retrieved November 24, 2015.
^ Jump up to: abDelaware Department of Transportation (1990). Official State Map(PDF) (Map). Dover: Delaware Department of Transportation. Retrieved November 24, 2015.
^ Jump up to: abcDelaware State Highway Department (1968). Official Highway Map(PDF) (Map). Dover: Delaware State Highway Department. Northern New Castle County inset. Retrieved November 24, 2015.
^Delaware State Highway Department (1967). Official Highway Map(PDF) (Map). Dover: Delaware State Highway Department. Retrieved November 24, 2015.
^Delaware Department of Highways and Transportation (1971). Delaware Highways Official Map(PDF) (Map). Dover: Delaware Department of Highways and Transportation. Retrieved November 24, 2015.
^Delaware Department of Transportation (1988). Official State Highway Map(PDF) (Map). Dover: Delaware Department of Transportation. Retrieved November 24, 2015.
^Delaware State Highway Department (1966). Official Highway Map(PDF) (Map). Dover: Delaware State Highway Department. Retrieved November 24, 2015.
^Delaware Department of Transportation (2008). Delaware Official Transportation Map(PDF) (Map). Dover: Delaware Department of Transportation. Retrieved November 24, 2015.
^ Jump up to: abDelaware Department of Transportation Division of Planning Cartographic Information Section (1994). Delaware Official State Map(PDF) (Map). Dover: Delaware Department of Transportation. Retrieved November 24, 2015.
^Delaware Department of Transportation (2017). Official Travel & Transportation Map(PDF) (Map). Dover: Delaware Department of Transportation. Retrieved August 18, 2019.
^ Jump up to: abDelaware State Highway Department (1969). Official Highway Map(PDF) (Map). Dover: Delaware State Highway Department. Retrieved November 24, 2015.
^ Jump up to: abDelaware Department of Transportation (1985). Official State Highway Map(PDF) (Map). Dover: Delaware Department of Transportation. Retrieved November 24, 2015.
^ Jump up to: abDelaware State Highway Department (1952). Official Highway Map of Delaware(PDF) (Map) (1952–1953 ed.). Dover: Delaware State Highway Department. Retrieved November 24, 2015.