Before 1932, the segment between Route 4 and US 44 was called State Highway 312.

On Jan. 1, 1932, SH 312 became Route 49, a number that fit in with other highways (41, 43, 45, 47) in the area. On May 1, 1954, Route 72 was extended from Plymouth to the state line via Torrington, incorporating all of former Route 49. In 1963, planners in the state highway reclassification decided a long Route 72 was not useful, and truncated it to Route 4 in Harwinton. The old Route 72 north of Route 4 got a new, rhyming designation: Route 272.

Route 372 is also a former alignment of Route 72.

• "Extended routes will cause two number changes." Hartford Courant, Apr. 25, 1954.

• Route 272 Ends (Photos; Doug Kerr at state-ends.com)
• Route 272 - Google Maps