By 1926, the piece of current NY 9N from Hague to Ticonderoga was designated as the easternmost leg of NY 47, which continued west to Chestertown on modern NY 8. In 1927, most of NY 6 north of Round Lake was replaced by US 9 when U.S. Highways were first signed in New York. The lone exception was between Elizabethtown and Keeseville, where US 9 followed a previously unnumbered highway to the east instead. The bypassed section of NY 6 between the two locations was redesignated as NY 9W at this time. NY 9W was renumbered to NY 9N as part of the 1930 renumbering of state highways in New York, eliminating the alphanumerical duplication between itself and US 9W.