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.

GTR's objective was to have a mainline from shipping ports in Portland, Maine, to rail connections in Chicago through the southern part of the Province of Canada that would serve Toronto and Montreal.

[3][4] In 1859 the Grand Trunk completed its route to Sarnia, Canada West, and began a ferry service across the St. Clair River to Port Huron.

[4] It was on the line from Port Huron to Detroit that a 12-year-old Thomas Edison held his first job as a newsboy and candy butcher onboard passenger trains.

However, Vanderbilt owned the Chicago and Northeastern section of the route from Flint to Lansing and charged Grand Trunk higher rates to move its freight over the line.

[5] GTW eventually took complete control of the line when it bought Nickel Plate's half interest from its successor Norfolk and Western Railway in 1981.

By the 1970s Detroit Terminal was suffering financial losses, and GTW negotiated to sell its share to NYC's successors Penn Central and Conrail until it dropped its ownership in 1981.

The St. Clair Tunnel, completed in 1891, approximately 6,000 feet (1,800 m) long and hand-dug, allowed Grand Trunk to discontinue its ferry service across the river.

That same year, Grand Trunk Western bought its headquarters building at 131 West Lafayette Avenue in downtown Detroit.

After several years of Canadian National subsidizing the financial losses of Grand Trunk Western, a new holding company would be established by CN in 1971 to manage GTW.

The Grand Trunk Corporation was created to shift full control of GTW operations to Detroit and begin a strategy to make the railroad profitable.

After petitioning the Interstate Commerce Commission, GTW won approval over a joint bid by Norfolk and Western and Chessie System to acquire the DT&I in June, 1980.

As part of the ICC's approval, GTW was obligated to divest its half or buy Norfolk and Western's share in the Detroit and Toledo Shore Line.

[6] Grand Trunk Western sought to further expand its trackage by seeking to purchase one of the bankrupt Midwest railroads, the Milwaukee Road or the Rock Island, in the 1970s.

After inspecting the Rock Island's property and finding its trackage in need of costly repairs, GTW turned its attention in 1981 to acquiring the Milwaukee Road.

GTW saw the acquisition of the Milwaukee Road (shorn of its Pacific Coast Extension and many of its midwestern branchlines) as an opportunity to expand its route further south and west to rail interchanges in Kansas City, Missouri, and Louisville, Kentucky.

Instead of initially placing a bid for the Milwaukee Road and seeking immediate ICC approval, GTW embarked on a strategy to improve the line's revenue and track maintenance.

GTW would eliminate all of the former Pontiac, Oxford and Northern line north of General Motors' Lake Orion manufacturing plant by 1985.

[12] In 1987, the former Cincinnati, Saginaw, and Mackinaw and the former Detroit, Grand Haven and Milwaukee routes north of Durand were sold to the Central Michigan Railway.

By the year 2000, engine terminals and maintenance facilities had also been eliminated or downsized in Chicago, Detroit, Durand, Pontiac, Port Huron and Battle Creek.

In December 1991, Canadian National announced a corporate image and restructuring program to consolidate all of its U.S. railroads under the CN North America brand.

However, while each railroad's locomotives would eventually receive CN's logo and black, red-orange and white paint scheme, they would still retain their respective reporting marks.

Despite the corporate re-branding, GTW's blue color scheme and its logo would persist on rolling stock and locomotives for several years while they were slowly either repainted or retired.

Grand Trunk Corporation, now formally headquartered at CN in Montreal, is the holding company for almost all of CN's U.S. properties, which include Grand Trunk Western, Illinois Central, Wisconsin Central, Duluth, Winnipeg & Pacific and Great Lakes Transportation, which includes the Bessemer & Lake Erie Railroad and the Duluth, Missabe and Iron Range Railway.

[5] Throughout its history, GTW has shared the same type and class designations of its locomotives with parents Grand Trunk Railway and Canadian National.

GTW also had a variety of other models of steam engines, including several 0-8-0 and 0-6-0 switching locomotives used to move rolling stock around in rail yards.

Three are park displays in Michigan; they include two 4-6-2 "Pacifics" at Durand and Jackson and an 0-6-0 at Sidney Montcalm Community College Heritage Village.

Amtrak's Detroit–Chicago trains now originate or terminate over this former commuter line, making stops in the northern Detroit suburbs of Pontiac, Troy and Royal Oak, Michigan.

Part of GTW's former route in Detroit, to Brush Street Station and its railcar ferry dock known as the Dequindre Cut, has been transformed into an urban greenway rail trail.

Wabash started its own service after 1910, when it acquired Michigan Central's ferries after that railroad opened the Detroit River Tunnel.