Michigan ranked 8th in population in the US with an estimated total of 10,050,446 in 2002, an increase of 1.1% since 2000. Between 1990 and 2000, Michigan's population grew from 9,295,297 to 9,938,444, an increase of 6.9%. The population is projected to reach 10.1 million by 2025. The population density in 2000 was 175 persons per sq mi.

Michigan was never inhabited by more than a few thousand Indians. As late as 1810, the non-Indian population of Michigan Territory was only 4,762. The late 1820s marked the start of steady, often spectacular, growth. The population increased from 31,639 people in 1830 to 212,267 in 1840 and 397,654 in 1850. Subsequently, the state's population grew by about 400,000 each decade until 1910, when its population of 2,810,173 ranked 8th among the 46 states. Industrial development sparked a sharp rise in population to 4,842,325 by 1930, pushing Michigan ahead of Massachusetts into 7th place.

In 2000, the national median age of Michigan's population was 35.5. In the same year, 26.1% of the population were under age 18 while 12.3% were age 65 or older. Approximately half of the state's population is concentrated in the Detroit metropolitan area.

Detroit has always been Michigan's largest city since its founding in 1701, but its growth, like the state's, was slow until well into the 19th century. The city's population grew from 21,019 in 1850 to 285,704 in 1900, when it ranked as the 13th-largest city in the country. Within the next 30 years, the booming automobile industry pushed the city up into 4th place, with a population of 1,568,662 in 1930. Since 1950, when the total reached 1,849,568, Detroit has lost population, dropping to 1,514,063 in 1970, 1,203,369 in 1980 and to 1,028,000 in 1990, when it held 7th place among US cities. The 2002 population was estimated at 925,051, putting Detroit in 10th place. As Detroit lost population, however, many of its suburban areas grew at an even greater rate. The Detroit metropolitan area totaled an estimated 5,469,312 in 1999, up from 4,320,203 in 1995 and 3,950,000 in 1960.

Other Michigan cities with estimated 2002 populations in excess of 100,000 include Grand Rapids with a population of 196,595; Warren, 137,672; Sterling Heights, 126,146; Flint, 121,007630; Lansing (the capital), 118,588; and Ann Arbor, 115,213.