It was 3 miles (4.8 km) long and located entirely within the town of Clifton Park.

The eastern terminus of NY 146B was in the hamlet of Groom Corners, where it met Miller and Sugarhill roads.

The route headed southeastward on Riverview Road, following the northern bank of the Mohawk River (also part of the Erie Canal) through the town.

It passed to the south of the Edison Country Club and remained on the riverbank to an intersection with Grooms Road approximately 1 mile (1.6 km) southeast of Rexford.

[4][5] The former routing of NY 146B is now part of CR 91, which continues eastward on Grooms Road to meet US 9 in the town of Halfmoon.