When the first set of posted routes in New York were assigned in 1924, the general routing of modern US 9 was designated as New York State Route 6, which went from the New York City line at Yonkers north to the Canadian border near Rouses Point. From New York City, NY 6 followed current US 9 north to Tarrytown, where it joined legislative Route 2 and continued north through Valatie to Albany via legislative Routes 1 and 2. North of Albany, NY 6 served Cohoes, Mechanicville, and Round Lake via modern NY 32 and NY 67. At Round Lake, NY 6 rejoined the path of current US 9 and headed north to Saratoga Springs. Past Saratoga Springs, NY 6 continued to Rouses Point on legislative Routes 22 and 25. NY 6 had two spur routes: NY 6A in Westchester County and NY 6B in Rensselaer and Saratoga counties.