Since the 1930s, the road between Center Groton and Ledyard center was an unsigned state road known as SR 588. In 1959, SR 588 was extended north using the Colonel Ledyard Highway to the village of Poquetanuck. Route 117 was established in 1963 as part of the 1962 Route Reclassification Act as a redesignation of old SR 588. One year later, the Route 117 designation was extended south to US 1 using a newly constructed extension of North Road. A portion of the current route in Ledyard used to be an old alignment of Route 27.