New York State Route 345

New York State Route 345
Map of northern St. Lawrence County with NY 345 highlighted in red
Route information
Maintained by NYSDOT and the village of Potsdam
Length	17.87 mi[1] (28.76 km)
Existed	1930[2]–present
Major junctions
South end	US 11 in Potsdam
North end	NY 37 in Waddington
Location
Country	United States
State	New York
Counties	St. Lawrence
Highway system
New York Highways Interstate US State Reference Parkways
← NY 344 → NY 346

New York State Route 345 (NY 345) is a state highway located entirely within St. Lawrence County in the North Country of New York in the United States. It is a north–south route connecting the towns of Waddington and Potsdam by way of the town of Madrid. The southern terminus of NY 345 is at an intersection with U.S. Route 11 (US 11) in the village of Potsdam. Its northern terminus is at a junction with NY 37 in the village of Waddington by the St. Lawrence River.

NY 345 was assigned as part of the 1930 renumbering of state highways in New York; however, it originally followed a different alignment south of the hamlet of Madrid. At the time, what is now NY 345 between Madrid and Potsdam was part of NY 56A. The NY 56A designation was eliminated in 1980. NY 345 was realigned two years later to follow old NY 56A to Potsdam as a result of a highway maintenance swap between the state of New York and St. Lawrence County. Ownership and maintenance of NY 345's original routing south of Madrid was transferred from the state to the county and the village of Canton as part of the exchange.