In 1931, State Highway 216 followed today's Route 49 and Route 14A from Stonington to the Rhode Island state line at Sterling. This is very close geographically to the modern Route 216, and I wondered if the number was retained because Rhode Island carried over its Route 216 from before 1932. The sources I have don't confirm this, though.

The modern Route 216 was commissioned between 1932 and 1934. Its original route (3.66 miles in Connecticut) was longer than today's:

• Putker Road, from Route 49 to Denison Hill Road
• Denison Hill Road to Clarks Falls Road
• Clarks Falls Road (today's Route 216) to the state line

However, the state-maintained portion at the time, as noted in 1938 correspondence with the American Association of State Highway Officials (AASHO), defined Route 216 as extending from the state line to 0.2 miles north of Clarks Falls.

In 1960, the state Committee to Reclassify All Public Roads recommended a shorter route, using Clarks Falls Road all the way from Route 49. In 1962, the state changed Route 216 to reflect that.