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.
History
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]
^ abcdeDelaware State Highway Department (1959). Official Highway Map of Delaware(PDF) (Map) (1959–1960 ed.). Dover: Delaware State Highway Department. Retrieved November 24, 2015.
^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.
^ 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.
^ abcDelaware Department of Highways and Transportation (1976). Delaware Highways Official Map(PDF) (Map). Dover: Delaware Department of Highways and Transportation. Retrieved November 24, 2015.
^ 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.
^ 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"(PDF) (Report). Washington, DC: American Association of State Highway and Transportation Officials. p. 538. Retrieved October 15, 2014 – via Wikisource.
^ abcdDelaware State Highway Department (1954). Official Highway Map of Delaware(PDF) (Map) (1954–1955 ed.). Dover: Delaware State Highway Department. Retrieved November 24, 2015.
^ abcdDelaware State Highway Department (1957). Official Highway Map of Delaware(PDF) (Map) (1957–1958 ed.). Dover: Delaware State Highway Department. Retrieved November 24, 2015.
^ abcMaryland State Highway Administration (1974). Maryland: Official Highway Map(PDF) (Map). Baltimore: Maryland State Highway Administration.
^ 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.
^ abMaryland State Highway Administration (1977). Maryland: Official Highway Map(PDF) (Map). Baltimore: Maryland State Highway Administration.
^ abDelaware Department of Transportation (1990). Official State Map(PDF) (Map). Dover: Delaware Department of Transportation. Retrieved November 24, 2015.
^ 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.
^ 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.
^ abDelaware Department of Transportation (2006). Delaware Official Transportation Map(PDF) (Map). Dover: Delaware Department of Transportation. Retrieved November 24, 2015.
^ abcDelaware Department of Transportation (1999). Delaware Official Transportation 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.
^ abDelaware State Highway Department (1969). Official Highway Map(PDF) (Map). Dover: Delaware State Highway Department. Retrieved November 24, 2015.
^ abDelaware Department of Transportation (1985). Official State Highway Map(PDF) (Map). Dover: Delaware Department of Transportation. Retrieved November 24, 2015.
^ abDelaware Department of Transportation (1981). Delaware Official State Highway Map(PDF) (Map). Dover: Delaware Department of Transportation. Retrieved November 24, 2015.
^ abDelaware State Highway Department (1952). Official Highway Map of Delaware(PDF) (Map) (1952–1953 ed.). Dover: Delaware State Highway Department. Retrieved November 24, 2015.