Grand Trunk Western Railroad

The Grand Trunk Western Railroad (GTWR, GT post-1960, AAR reporting mark GTW) is a U.S. railroad and primary subsidiary of Canadian National Railway (CN).

Created as a subsidiary to the Grand Trunk Railway (GTR), the GTWR ran from the St. Clair River at Port Huron, Michigan to Chicago, Illinois. After the GTR was absorbed into the Canadian National Railways (CNR) system in January, 1923, the GTWR became CNR's primary U.S. subsidiary and gave the company a strategic advantage with the direct connection to Chicago when compared to the route of its competitor Canadian Pacific Railway.

CNR (CN after 1960) underwent various corporate restructuring efforts in the post-war period which saw the corporate name Grand Trunk Western Railroad maintained for operating the U.S. portion of its mainline to Chicago, as well as several feeder lines in southern Michigan in the Detroit area, however this was later expanded to use the GTWR as a holding company to group several disparate lines in other states:

• A New England line running from the Canada-United States border at Norton, Vermont to Portland, Maine operated informally over the years as the Grand Trunk Eastern, however it was officially known as CN's Berlin Subdivision. It was sold to a short line operator in 1989, becoming the St. Lawrence & Atlantic Railroad.
• Duluth, Winnipeg and Pacific Railway came to be grouped under GTWR for a time.
• Detroit, Toledo & Ironton Railroad, which CN purchased from bankruptcy in the early 1980s, was grouped under GTWR.

As with the change to the CN acronym in 1960, GTWR changed to the shortened GT, using a logo of similar design to the CN "noodle". In 1995, CN underwent a rebranding exercise whereby the names of its U.S. subsidiaries, primarily GT, were removed from locomotives and rail cars, being replaced with the CN logo. The name "Grand Trunk" has not disappeared entirely as CN has continued to group its U.S. subsidiaries (Illinois Central, Wisconsin Central, Grand Trunk Western, and Duluth, Winnipeg and Pacific) under the "Grand Trunk Corporation" for legal or administrative purposes.