 In the mid-1960s, the Adirondack Northway was completed in the vicinity of Champlain, supplanting the northernmost of US 9.US 9 initially overlapped with I-87 from exit 43 to the Canadian border; however, it was truncated to end at exit 43—the last interchange before the border—in the 1970s.Part of US 9's former routing to the border was retained as a service road and was designated as NY 971B, an unsigned reference route.