Route 34 begins as the two-lane Berkshire Road in the Sandy Hook section of the town of Newtown, as a continuation of Washington Avenue (a town road). The road crosses under I-84 after a tenth of a mile, then intersects after another with Wasserman Way (SSR 490), which leads to ramps to/from I-84 at Exit 11. The road then heads east towards the Stevenson section of the town of Monroe, where the road name changes to Roosevelt Drive at the town line. After intersecting Route 111 (leading to Monroe center), Route 34 crosses the Housatonic River via the Stevenson Dam Bridge into the town of Oxford. Route 34 then follows the east banks of the Housatonic River as it traverses the towns of Oxford and Seymour. Route 34 soon enters the city of Derby, where it becomes Main Street after the intersection with Derby-Shelton Bridge Route 712, which leads to Route 110 in downtown Shelton. In downtown Derby, Route 34 has a junction with Route 8 at Exit 15 near the Derby-Shelton train station.