The route originates as the northernmost portion of the Trenton and New Brunswick Turnpike from Trenton to New Brunswick. The turnpike originated as a chartered highway in 1804, with the new roadway finished by 1806. The turnpike lived out its 99-year charter term, with the alignment of the turnpike turned over to local authorities in 1903. In 1927, the New Jersey State Highway Department designated State Highway Route 26 on the alignment of the turnpike, except for the portion on Jersey Avenue. This alignment was designated as Route 26A, a spur of State Highway Route 26 in 1941, and renumbered in the 1953 state highway renumbering as Route 91. The route has remained virtually untouched since.