NY 263 was realigned to overlap with NY 78 north to NY 31 in Lockport. Its former alignment east of NY 78 became a realignment of NY 268. In the early 1940s, NY 263 was extended southwest to Buffalo over NY 270. Initially, NY 263 overlapped with NY 270 along Millersport Highway; however, the overlap was eliminated in the late 1940s after NY 270 was truncated to begin at NY 263 in Getzville. NY 263 was cut back to its current northern terminus in Millersport on January 1, 1962. The route was re-extended to Clarence , replacing NY 268; however, the extension was short-lived as NY 263 was pulled back to its junction with NY 78 by 1977.