Because of Michigan's location, its inhabitants have always depended heavily on the Great Lakes for transportation. Not until the 1820s did land transportation systems begin to be developed. Although extensive networks of railroads and highways now reach into all parts of the state, the Great Lakes remain major avenues of commerce.
The first railroad company in the Midwest was chartered in Michigan in 1830, and six years later the Erie and Kalamazoo, operating between Toledo, Ohio, and Adrian, became the first railroad in service west of the Appalachians. Between 1837 and 1845, the state government sought to build three lines across southern Michigan, before abandoning the project and selling the two lines it had partially completed to private companies. The pace of railroad construction lagged behind that in other midwestern states until after the Civil War. Only then did the combination of federal and state aid and Michigan's booming economy lead to an enormous expansion in trackage, from fewer than 800 mi (1,300 km) in 1860 to a peak of 9,021 mi (14,518 km) in 1910. With the economic decline of northern Michigan and the resulting drop in railroad revenues, however, Class I trackage declined to 2,228 rail mi (3,585 km) by 2000. Most railroad passenger service is provided by Amtrak, which operates five trains through the state. Freight is carried by the state's 26 railroads. The Michigan state government, through the Department of Transportation, has helped to revive the railroad system through its Rail Program.
Railroads have been used only to a limited degree in the Detroit area as commuter carriers, although efforts have been made to improve this service. In the early 1900s, more than 1,000 mi (1,600 km) of inter-urban rail lines provided rapid transit service in southern Michigan, but automobiles and buses drove them out of business, and the last line shut down in 1934. Street railway service began in a number of cities in the 1860s, and Detroit took over its street railways in 1922. Use of these public transportation systems declined sharply after World War II. By the 1950s, streetcars had been replaced by buses, but by 1960 many small communities had abandoned city bus service altogether. During the 1970s, with massive government aid, bus service was restored to many cities and was improved in others, and the number of riders generally increased. In fiscal year 1995/96, local public transit systems handled 82.5 million passengers while inter-city bus systems carried an estimated 350,000 passengers.
As of 2000, the state had 91,927 mi (147,942 km) of rural roads and 30,007 mi (48,291 km) of urban roads. Major expressways included I-94 (Detroit to Chicago), I-96 (Detroit to Grand Rapids), and I-75 (from the Ohio border to Sault Ste. Marie). In 2000, there were 5,023,421 registered passenger cars, 3,386,473 trucks, 25,827 buses, and 183,592 motorcycles. Licensed drivers numbered 6,925,246 during the same year.
The completion in 1957 of the Mackinac Bridge, the 4th-longest suspension span in the world, eliminated the major barrier to easy movement between the state's two peninsulas. The International Bridge at Sault Ste. Marie, the Blue-Water Bridge at Port Huron, the Ambassador Bridge at Detroit, and the Detroit-Windsor Tunnel link Michigan with Canada.
The opening of the St. Lawrence Seaway in 1959 made it possible for a large number of oceangoing vessels to dock at Michigan ports. In 2000, the port of Detroit handled 17.3 million tons of cargo; Presque Isle, 10.7 million tons; Escanaba, 8.6 million tons;and the limestone-shipping port of Calcite, 8.5 million tons.
Michigan was a pioneer in developing air transportation service. The Ford Airport at Dearborn in the 1920s had one of the first air passenger facilities and was the base for some of the first regular airmail service. In 2002, the state had 380 airports, 85 heliports, 2 stolports, and 7 seaplane bases. The major airport is Detroit Metropolitan Wayne County Airport, with 17,326,775 enplaned passengers in 2000.