In the 1920s, State Highway 104 followed today's Route 17 between Glastonbury Center and today's Route 66 in Portland.
In 1932, Route 104 was commissioned as an 8.40-mile route from US 1 to the New York state line:
- Bedford Street (and Summer Street?), from US 1 to Long Ridge Road (today's Route 104)
- Long Ridge Road (today's Route 104) into New York
USGS maps in 1947 and 1951 appear to show Route 104's southern segment shifted from Bedford Street to Summer Street. However, today these streets are an opposing one-way pair; if that was true decades ago, then Route 104 traffic would have used both.
At some point later, Route 137 was extended south along Washington Blvd. to US 1. Route 104's southern end was truncated to Route 137, so now Route 104 extends along Long Ridge Road only.
Also, possibly around 1976, a realigned 1.3-mile section of Route 104 opened in northern Stamford. The older section is now Old Long Ridge Road.
Circa 2008, the small, tight 4-ramp interchange at the Merritt Parkway was reconstructed. The two loop ramps remain; but the diagonal ramps were lengthened, and a new ramp from Route 104 northbound to the Parkway northbound was added.
Route 104 freeway?
In 1963, an assistant chief planner at the state highway department announced in Darien that "three major expressways" were planned in the area in the "foreseeable future". These were:
- US 7 from Norwalk to Wilton
- I-87 (now I-684)
- "The new Rte. 104 in Stamford, following the present line of Long Ridge Road and connecting points as far north as Bedford, N. Y. with the Connecticut Turnpike."
There were a few area proposals for a north-south highway between Stamford and Pound Ridge, N. Y. or Bedford, N. Y. In 1956, the Westchester Planning Department proposed a high-speed "Stamford - Bedford Village Road" between Routes 104 and 137, though noting that the route "might be cancelled." In 1969, Westchester County proposed a freeway upgrade to Route 137.
No north-south freeway in Stamford was built (I-95 and Route 15 are locally east-west), and no such plans are active now.