Route 33 originally was part of two auto trails: the Cranbury Trail, an alternative to the Lincoln Trail running from New Brunswick to Trenton; and the Jersey Link, running from Hightstown to Ocean Grove. These routes were incorporated in 1916 into two new routes: New Jersey Route 1 in parts of the road south of Hightstown, and Route 7 from Hightstown to its terminus at Route 71. Both roads were changed into Route 33 in the 1927 New Jersey state highway renumbering.