Connecticut Route 123

Route 123
Map of Fairfield County in southwestern Connecticut with Route 123 highlighted in red
Route information
Maintained by ConnDOT
Length:	8.37 mi (13.47 km)
Existed:	1932 (realigned 1934) – present
Major junctions
South end:	US 1 in Norwalk
	Route 15 in Norwalk US 7 in Norwalk
North end:	NY 123 in Lewisboro, NY
Location
Counties:	Fairfield
Highway system
Routes in Connecticut Interstate U.S. State SSR SR ← Route 122 Route 124 →

Route 123 is a secondary state highway in southwestern Connecticut from Norwalk to the New York state line near the hamlet of Vista (Town of Lewisboro).

Route 123 begins at an intersection with US 1 in Norwalk and heads northwest, intersecting with US 7 and continuing across the Norwalk River. It then runs through the Silvermine neighborhood near an interchange with Route 15 (Merritt Parkway) at the Norwalk-New Canaan town line. It continues north through New Canaan, ending at the New York state line and continuing as NY 123.

The road from Central Norwalk via New Canaan center to the New York state line was designated as State Highway 184 in 1922. Route 123 was commissioned in 1932 from the southern half of old Highway 184 (Norwalk to New Canaan) and a previously unnumbered road from there to the state line. It originally began at US 1 and ran along Riverside Avenue on the west bank of the Norwalk River to New Canaan Avenue, then from there to the state line along modern Route 123. The northern half of old Highway 184 became part of Route 29 (now Route 124). However, the portion between Norwalk and New Canaan was originally shown as Route 29 in the 1932 official highway map, with Route 123 shown along modern Route 124 between Darien and New Canaan. In 1934, the Routes 123 and 29 south of New Canaan were exchanged for each other.