The Rome, Watertown and Ogdensburg Railroad was a railroad that grew, in stages, from Rome, New York to Watertown and then to Ogdensburg, New York and Massena, New York. The original Rome and Watertown Railroad terminated in Cape Vincent, NY on the St. Lawrence River. A branch of the Rome, Watertown and Ogdensburg Railroad, commonly known as "The Hojack Line", operated along the south shore of Lake Ontario, from Oswego, New York to Niagara Falls, New York.
After it was merged into the New York Central in 1913, the RW&O line was known as the St. Lawrence Division.