Commissioned in 1932, Route 87 originally extended to Bolton Notch along today's US 6, while US 6 followed a northerly route using today's Route 31. In 1934, the road from Bolton Notch to Andover became part of US 6A, and Route 87's northern end was cut back to where it is now.
The Trumbull Highway in 1935 followed today's US 44, US 6, Route 87, and Route 2 from the New York border to the Rhode Island border: over 100 miles. But today, the only traces are the street names for US 6 and Route 87 in Andover and Columbia.
I-87 nearly forces renumbering
Route 87 enjoys a bit of history unique to the state's highways: it almost lost its number to an interstate highway, but got a reprieve when the interstate changed its number instead.
In Connecticut, no two highways can share the same number: for example, when I-91 was created, old state route 91 had to be renumbered. (State route 95, which acted as a continuation of I-95 until that highway was completed, was an intentional exception.) On October 30, 1968, a section of I-87 cutting through a corner of Greenwich opened, meaning Route 87 would have to be renumbered.
In May 1969, the state informed towns along the route that as of July 31, Route 87's designation would be changed to Route 287. (Using a "rhyming" number for changes was a common practice, and today's Route 287 in Wethersfield did not yet exist.)
However, officials in New York announced their intent to move the I-87 designation to the New York State Thruway, and give the segment affecting Connecticut a new number: I-684. If that were approved, Connecticut's Route 87 would be spared. In August 1969, the Connecticut DOT said the CT 87 to CT 287 change was on hold pending the outcome of the New York plan.
In 1970, the I-87 leg was renumbered to I-684. On Feb. 1, 1970, ConnDOT announced that CT 87 would keep its number.
There's a short street in Franklin called "Old Route 87," suggesting a slight rerouting, but I don't have further information.
Scenic Route Advocacy
In late 2003, the Columbia Conservation Commission was working to have Route 87 nominated as a scenic road. This would help protect the road from widening efforts. The process, which starts with public discussions in town, would take several months, including a possible formal application to the state the following spring.