In the 1920s, part of Route 187 (between Route 189 in North Bloomfield and Route 168 in Suffield) was called State Highway 328. Another part, between US 44 in Hartford and Park Ave in Bloomfield, was part of the old SH 311.
In 1932, Route 187 was commissioned, extending north from the old Route 9 (now Route 189) in North Bloomfield to the Massachusetts state line, for a length of 10.83 miles in-state. Its original route:
- Spoonville Road, from Tariffville Road (old Route 9/189) at the north side of the Spoonville Bridge (which is now gone) to Seymour Road in East Granby
- Seymour Road, from Spoonville Road to S. Main Street (today's Route 187)
- Today's Route 187, north through Suffield into Massachusetts
1947: Trade offer for Route 218 declined
In 1947, Bloomfield officials submitted a bill to have the state accept Blue Hills Avenue Extension, a portion of today's Route 187 north of Park Avenue, into the state highway system. Gov. McConaughy vetoed the bill, saying the two population centers served by the road were already served by parallel trunk routes (such as Route 9, which is now Route 189).
Gov. McConaughy also noted that the state had offered to turn over the Cottage Grove Road portion of Route 218 to the town in return for the Blue Hills segment, but that offer had been declined.
In a general note attached to his veto, he criticized the recent practice of the Legislature to prod the Highway Commissioner into incorporating more and more local roads into the state system. He concluded: "I believe the interests of the whole state should take precedence over the desires of the local community, as much as I would like to sign each bill that improves local roads."
A new Farmington River bridge, and leaving Spoonville Road
Until the mid-1950s, Route 9 (now Route 189) followed Tunxis Avenue from North Bloomfield to Tariffville, crossing the Farmington River once into East Granby and back again into Tariffville. In 1954, the state discussed plans to relocate Route 9 to the opposite bank of the river, eliminating the double crossing. Route 187 would still cross the river to end at Route 9.
In August 1955, Mother Nature took the initiative on some demolition work, as floods washed away several bridges along the Farmington River – including both bridges the new Route 9 was to bypass. Temporary bridges were built to carry Route 9 across to the Route 187 junction in East Granby and back across toward Tariffville. In early 1957, the state conducted another hearing in East Granby about proposed changes to the area.
Route 9 would stay on the south side of the river, and a new bridge to the west would carry Route 187 across. In East Granby, Route 187 would be relocated to the west, away from the village of East Granby, to meet existing Route 187 somewhat north of Hatchett Hill Road. The new road would be safer, and Spoonville Road would be quieter with less through traffic.
On Jan. 11, 1960, the new Route 187 roadway and bridge opened to traffic, as well as a short segment of four-lane Route 9 freeway in North Bloomfield (which is now part of Route 189 and 187). The new roadway was two lanes and limited access, leading from a trumpet interchange at Route 9, across the river, to Hatchett Hill Road (today's SR 540).
Route Reclassification: Extension to Hartford
The segment of today's Route 187 south of the 187/189 split in North Bloomfield was added in 1963. Before that, most of it was a state road under different names. From US 44 to Park Avenue, it was part of the old Route 184, dating back to 1932. North of there (starting in 1935), the road was unsigned SR 921. In 1963, Route 187 was extended southward from the Tariffville Road exit on Route 189 to its modern terminus at US 44. The old Route 184 and SR 921 were decommissioned.
Widening in Bloomfield
In the late 1970s, Route 187 was widened to four lanes between Route 218 and Park Avenue. In the 1980s, however, it was significantly improved in the office park area of North Bloomfield, and is now four lanes divided between Route 305 and the 187/189 merge.
Around the same time, a new T-intersection was built for the southern 187/189 junction. Tariffville Road in the area is no longer part of Route 187.