Grand Trunk Western is the American arm of Canadian National (CN; AAR reporting mark CNA) operating in Michigan, Illinois, Indiana and Ohio. Since a corporate restructuring by CN in 1971 the railroad has been under a subsidiary holding company known as the Grand Trunk Corporation.

Grand Trunk Western’s mainline, known as its Chicago Division, runs between Chicago, Illinois and Port Huron, Michigan. It serves as a connection between the railroad interchanges in Chicago and the rail lines in eastern Canada and the Northeastern United States. The railroad also has extensive trackage in Detroit, Michigan, and Ohio. Its presence in Detroit has made the railroad an essential link for the automotive industry. GTW has become known as a major hauler of parts and autos from manufacturing plants around Detroit and across Michigan.