No longer assigned; commissioned in 1932, Route 129 connected downtown New Milford with the northern village of Merryall. Its route, south to north, was 6.79 miles:

• Railroad St. from Bridge St. (today's US 202/Route 67) to Wellsville Ave.
• Wellsville Ave. to Merryall Rd.
• Merryall Rd. (rebuilt by the state in 1928) to Bear Hill Rd. (village of Lower Merryall)
• Bear Hill Rd. to Squire Hill Rd.
• Squire Hill Rd. to Chemiske Rd. (old Route 130)

Route 129 served the old Mica Quarry, which even by 1935 had been abandoned. From 1932 to 1940, it ended at Route 130 there; Route 130 was soon abandoned as well. The former intersection of routes 129 and 130 is probably very quiet these days.

Route 129 disappeared from the official state highway map in 1941, but reappeared in 1942. It was turned over to the town in 1963.