 NY 156 was assigned as part of the 1930 renumbering of state highways in New York to what is now NY 146 from Gallupville to Altamont and its modern alignment from Altamont to Voorheesville.The alignments of NY 146 and NY 156 west of Altamont were flipped , placing both routes on their modern alignments.NY 156 originally followed NY 85A southeastward from Voorheesville to New Scotland, where both routes ended at NY 85.