In the 1920s, State Highway 115 followed today's Route 185.

The modern Route 115 was commissioned in 1932, and was slightly shorter than today: 5.35 miles instead of 5.66. Its north end was at Bank Street in Seymour, which was first Route 8, and then in 1936, Route 8A.

In 1962, Route 8A was deleted, and Route 115 was extended along Main Street to Route 67.

• Connecticut Department of Transportation. "Route change table.xls". Microsoft Excel spreadsheet file, received April 4, 2008.

Route 115 Ends (Photos; Doug Kerr at state-ends.com)