Route 45 was commissioned in 1932, from the old State Highway 152. The road has seen no changes since then. Even its official length to the nearest 1/100th of a mile has remained constant since 1942 (the earliest such information I have).

"The History of Connecticut Route 45" would make a very short book.

There was one thing they wanted to do...

In 1970, a public hearing was conducted in the town of Washington to discuss a proposed realignment of Route 45, between Route 25 (now US 202) and West Shore Road, SR 478. Route 45 here threads a narrow valley of the East Aspectuck River. The impetus for the proposed improvements was safety rather than capacity.

The state examined three alternatives. One was discarded because it involved relocating the river, harming its scenic value. Another alternative, moving Route 45 away from the river, would damage several properties (as would the first option). The third option -- fixing Route 45 mostly in place -- was recommended.

The three-way "Y" intersection with Route 25 would be preserved, but realigned to a better angle. Between Main Street No. 2 and New Preston Hill Road, Route 45 would be shifted to the east, cutting into a ridge, to improve sight distance. To the north, Route 45 would continue slightly east of its current alignment, with some retaining walls needed. In all, the new Route 45 would be two lanes, 30 feet wide, with 6 foot graded (but not paved) shoulders.

It appears this realignment was not done; at least from maps, Route 45 looks today much the same as in the 1950s.