The state took over the road at the beginning of the 20th century. In 1922, when route numbers were first publicly signed in the New England region, the route from New Haven to the village of Sandy Hook was designated as State Highway 117. The road followed the Derby Turnpike and the remaining portion of the Ousatonic Turnpike to the village of Stevenson, then the rest of modern Route 34 to Sandy Hook. In the 1932 state highway renumbering, old Highway 117 was renumbered to Route 34 with an additional westward extension to the city of Danbury. At the time, Route 34 overlapped with US 6 into the borough of Newtown, then used modern Route 302 to Bethel and modern Route 53 to downtown Danbury. In 1935, US 202 was established and used the original path of Route 34 between Danbury and Newtown. Route 34 was cut back to end at US 6 in Sandy Hook.