The new US route used the entirety of Ridge Road from Lewiston to Red Creek, save for small portions in and around the city of Rochester; as a result, NY 31 was shifted south onto most of its modern alignment while NY 3 was rerouted south of Watertown to follow what had been NY 3D. When US 104 was first assigned, it dipped south to serve downtown Rochester instead of bypassing it to the north.
The new US route covered the entire length of Ridge Road from Lewiston to Red Creek, excluding small sections within and around Rochester; as a result, NY 31 was shifted south onto most of its current alignment while NY 3 was rerouted south of Watertown to follow what had been NY 3D. When US 104 was first assigned, it dipped south to serve downtown Rochester instead of bypassing it to the north.