- Southern Terminus:
- Fort Hill Road (US 1) in Groton
- Northern Terminus:
- Norwich-Westerly Road (CT 2) in Preston
- 11.32 miles
- New London
CT 117 is a north/south route from Groton to Preston. It begins at Fort Hill Road (US 1) and runs north through Ledyard to Preston, where it joins CT 2A. The two routes are multiplexed along Hallville-Poquetanuck Road to Norwich-Westerly Road (CT 2), where both end.