The four-lane section in Derby, Orange, and West Haven was opened in 1940. In the 1940s, Route 34 ended at Sherman Avenue (former US 5 and Route 10). The Oak Street Connector appeared in state highway plans in the mid-1950s and the present expressway opened in 1960. When the expressway opened, Route 34 was designated on it. Route 34 was assigned onto city streets (Chapel Street and George Street) to connect with the original eastern end. When North Frontage Road was completed, Route 34 was relocated onto it via an overlap with current Route 10.