New York State Route 31D

New York State Route 31A
Map of western New York with NY 31A highlighted in red
Route information
Auxiliary route of NY 31
Maintained by NYSDOT
Length:	22.89 mi (36.84 km)
Existed:	c. 1935 – present
Major junctions
West end:	NY 31 / NY 63 in Medina
East end:	NY 19 Truck / NY 31 near Brockport
Location
Counties:	Orleans, Monroe
Highway system
New York Highways Interstate U.S. State Reference Parkways ← NY 31 NY 31B → ← NY 31C NY 31E →

New York State Route 31A (NY 31A) is an east–west state highway located in the western part of New York in the United States. It serves as a southerly alternate route of NY 31 from the western part of Orleans County to the far western part of Monroe County. It diverges from NY 31 south of the village of Medina and parallels NY 31 eastward until it reconnects to its parent route southwest of the village of Brockport. While NY 31 passes through the villages of Medina, Albion, and Holley, NY 31A bypasses all three, serving sparsely populated areas to their south instead. The route intersects NY 98 south of Albion and NY 237 in Clarendon.

The origins of NY 31A date back to the 1930 renumbering of state highways in New York when the section of modern NY 31 between Middleport and Medina was designated as NY 3A. It was renumbered to NY 3B c. 1932 and extended northeastward to Knowlesville via Millville by 1932 before becoming NY 31A c. 1935. NY 31A was cut back to its current western terminus in 1949 and extended eastward to NY 19 and NY 31 in Brockport c. 1963, replacing New York State Route 31D, a spur route linking NY 31 to the Monroe–Orleans county line. The route was truncated to its current eastern terminus in the early 1980s after NY 31 was altered to bypass Brockport to the southwest.