Connecticut Route 55

Length 125.09 miles; 2.64 miles in Connecticut
From the Pennsylvania state line at Barryville, N. Y.
To US 7 in New Milford

Route 55 is really New York's highway, where 98% of it is located. Go check out its Wikipedia page.

Welcome back! I do have a few things to say about it from Connecticut's point of view:

it's one of the longest shared state routes (behind Route 8, Route 10, Route 12, and Route 32, which were all New England Interstate routes)
it travels the furthest west of any state route from Connecticut
Doug Kerr has 21 photos of it (and more than 680,000 photos of other things)

CT 55 History

Route 55 was commissioned in 1932, from the earlier State Highway 129, and has had no changes in Connecticut. The route was designated earlier in New York state, in 1930.

CT 55 Links

CT 55 photos (Doug Kerr)
CT 55 photos (David Golub)
New York state route 55 (Wikipedia)