Route 207 was commissioned in 1932, and has seen a few changes to its alignment:

• Original: Route 87 in Franklin to Route 97 in Sprague.
• Circa 1941: extended westward to Route 85. Through most or all of the 1940s, Route 207 was 17.35 miles long, leading from Route 85 to a terminus at the Sprague-Norwich town line on High Street. Officially it did not intersect Route 97, but came close (see map scan, below).
• 1961: a portion in Franklin, from 0.75 mile east of Route 32 to 0.12 mile west of the town line with Sprague, was significantly realigned and built with a shallower grade, by use of extensive cuts and fills. The project began March 2 and finished December 11, at a cost of $555,000.

it ran parallel for a while, ending at the Norwich town line. This is a USGS 1946 map scan from University of New Hampshire, Dimond Library, Documents Department and Data Center.

Route 207's strange eastern end, 1940s

In the 1940s, Route 207 officially never made it as far as Route 97; instead,

Renumber as part of extended Route 138, which would also take over Route 16 to East Hampton.

• Connecticut State Highway Department. Routes and Road Numbers on the State Highway System, Showing Control Numbers and Sections. Dated Jan. 1, 1942, Jan. 1, 1944, and May 1, 1947.
• "Route 207 nears completion." Connecticut Highways, Summer 1961.

• Route 207 Ends (Photos; Doug Kerr at state-ends.com)
• Route 207 - Google Maps