It was established to consolidate existing companies in the northern part of the state and to complete a north–south railway line along the west side of Lake Champlain.

The backers of the Whitehall and Plattsburgh Railroad had attempted to establish a railway line along the west side of Lake Champlain via the Ausable River valley.

New York State Assemblyman Smith Mead Weed, and Rensselaer and Saratoga Railroad president Isaac V. Baker Jr., persuaded the Delaware and Hudson Railway to back a new effort to build the line.

[6] The difficult terrain between Port Henry and Plattsburgh required an additional year and that part of the line opened on November 29, 1875.

[10][12] A final shortening of the route to Montreal occurred with the building of the Napierville Junction Railway and subsequent D&H control.