New York State Route 420

New York State Route 420
Map of northeastern St. Lawrence County with NY 420 highlighted in red and NY 970B in blue
Route information
Maintained by NYSDOT
Length	11.92 mi[1] (19.18 km)
Existed	1930[2]–present
Major junctions
South end	US 11 in Stockholm
North end	NY 37 in Massena
Location
Country	United States
State	New York
Counties	St. Lawrence
Highway system
New York Highways Interstate US State Reference Parkways
← NY 419 → NY 421

New York State Route 420 (NY 420) is a north–south state highway in St. Lawrence County, New York, in the United States. The southern terminus of the route is at an intersection with U.S. Route 11 (US 11) in the town of Stockholm. Its northern terminus is at a junction with NY 37 in the village of Massena. NY 420 passes through undeveloped regions of St. Lawrence County for most of its routing and briefly overlaps with NY 11C in the hamlet of Winthrop.

NY 420 was originally part of Route 32, an unsigned legislative route created by the New York State Legislature in 1908. The Winthrop–Massena portion of Route 32 became part of the signed NY 56 in the mid-1920s; however, NY 56 was realigned in 1927 to follow a new alignment well to the south of Winthrop. The former routing of NY 56 between Winthrop and Massena was redesignated as NY 420 as part of the 1930 renumbering of state highways in New York. NY 420 was extended southward to its current terminus south of Winthrop in 1980.