The Grand Trunk Western Railroad Company was an American subsidiary of the Grand Trunk Railway, later of the Canadian National Railway operating in Michigan, Illinois, Indiana, and Ohio. Since a corporate restructuring in 1971, the railroad has been under CN's subsidiary holding company, the Grand Trunk Corporation. Grand Trunk Western's routes are part of CN's Michigan Division. Its primary mainline between Chicago and Port Huron, Michigan serves as a connection between railroad interchanges in Chicago and rail lines in eastern Canada and the Northeastern United States. The railroad's extensive trackage in Detroit and across southern Michigan has made it an essential link for the automotive industry as a hauler of parts and automobiles from manufacturing plants.

Owosso is the largest city in Shiawassee County in the U.S. state of Michigan. The population was 14,714 at the 2020 census. The city is mostly surrounded by Owosso Township on its west, but the two are administered autonomously. The city was named after Chief Wosso, an Ojibwe leader of the Shiawassee area.