In the 1920s, State Highway 149 followed the old Route 15 path (now covered by I-84) between Route 32 and the Massachusetts state line. In 1930 or 31, this became part of SH 105.

The modern Route 149 was commissioned in 1932, renumbered from the 1920s SH 148. There have been no changes since then, although a fun 1953 Rand McNally typo extended the route north along Jones St. and Burrows Hill Rd. to Route 66.

There is an "Old East Haddam Road" paralleling Route 149 in that town, but that appears not to be an old alignment of Route 149.

Urban Renewal in Moodus

At the eastern corner of Route 149 and Route 151 is the village of Moodus, where there once was a small but dense town center, with several businesses and street parking. In 1967, enticed by federal and state urban renewal funds, residents voted to demolish downtown and build a new, improved retail center 1/4 mile to the east. East Haddam was one of the smallest towns in the United States to participate in urban renewal, and the results were disappointing. The Nathan Hale Plaza shopping center and nearby suburban-styled businesses are what remain. Many historians and long-time residents wish they could take this one back.