The Plattsburgh and Montreal Railroad was a railway company that operated in the state of New York in the mid-19th century.

The southern half of the company's line is part of the Canadian Pacific Kansas City's Canadian Subdivision; the Delaware and Hudson Railway abandoned the rest in 1925.

It was part of a scheme with the Lake St. Louis and Province Line Railway and Montreal and Lachine Railroad to construct a new line between Plattsburgh, New York, and Montreal.

The line opened between Plattsburgh and Mooers on July 26, 1852, and to the Canadian border on September 20.

At the time, no railway extended south from Plattsburgh, but steamboats operating on Lake Champlain provided a connection with Burlington, Vermont, and other destinations.