It parallels the Southern Tier Expressway (NY 17 and Interstate 86 or I-86) very closely for its entire length.

The route heads northeast through the town of Hinsdale along the base of a valley surrounding Oil Creek.

[3] Near the Cattaraugus–Allegany county line, Route 446, Oil Creek, and the WNYP all turn east toward Cuba; however, the expressway continues on a northeasterly alignment to bypass the village to the north.

[7] NY 63 was rerouted south of Mount Morris in the early 1940s to follow its current alignment to Wayland.

[8][9] In the early 1970s, construction began on the portion of the Southern Tier Expressway between Olean and Corning.