US 20 was realigned to follow its modern routing between Hamburg and Avon. Its former alignment between Hamburg and Geneseo became part of NY 20A, which continued north from Geneseo to Avon over NY 20D. By the following year, the Hamburg–Geneseo segment of NY 20A was included in the new US 20A while the Geneseo–Avon portion became part of a realigned NY 254. The routings of NY 39 and NY 245 east of Pike were swapped in the fall of 1939, placing NY 245 on a routing extending from Pike to Geneva and NY 39 on its modern alignment to Leicester. NY 39 was also extended northeast to Avon as part of the change, supplanting NY 254. The portion of NY 39 within Avon was rerouted to follow Wadsworth Avenue to West Main Street (US 20 and NY 5) in the early 1950s.