In the 1920s, State Highway 121 followed today's US 44 from US 7 to the New York state line. This road became Route 199 in 1932, and part of US 44 in 1935.

The modern Route 121, commissioned in 1932 from the old SH 195, hasn't changed since then, except for getting shortened when US 1 moved from Cherry Avenue to the Boston Post Road in Milford.

Route 121 is blown off (no interchange) by I-95. Also, Craig Fenn reports that a CT 121 marker on the beginning of the southbound route (just past Route 34) uses a white circle on a black square, a la New Jersey.

• Fenn, Craig W. "A couple road tidbits." Email to Kurumi, Oct. 23, 2000.

• Route 121 Ends (Photos; Doug Kerr at state-ends.com)