New York State Route 126 (NY 126) is a 28.56-mile-long (45.96 km) state highway in the North Country of New York in the United States. It proceeds in a roughly northwest to southeast direction between NY 12 at the eastern city line of Watertown in central Jefferson County and NY 812 in the village of Croghan in northern Lewis County. In between, NY 126 serves the adjacent villages of West Carthage and Carthage, where the route has overlaps with NY 3 and NY 26. Most of the route passes through rural areas, and the portion southeast of Carthage parallels either the Black River or a tributary of it.

New York State Route 12 (NY 12) is a state highway extending for 222.27 miles (357.71 km) through central and northern New York in the United States. The southern terminus of the route is at U.S. Route 11 (US 11) in the town of Chenango in the Southern Tier. The northern terminus is at NY 37 near the village of Morristown in the North Country. In between, the route serves three cities of varying size: Norwich, Utica, and Watertown. NY 12 intersects several primary routes, including US 20 in Sangerfield, New York State Thruway via Interstate 790 (I-790) in Utica, overlaps NY 28 from Barneveld to the town of Remsen, NY 3 in Watertown, and I-81 in Pamelia and Orleans.