In Michigan, the growth of cities was slower up to 1910 than in its neighboring states. Since 1910, the reverse had been true. The more rapid growth of urban population in the state since 1910 is attributable largely to the automobile industry and its high degree of concentration in Michigan. The influx of people to work in the automobile plants brought drastic changes in the character of the state's population. Only California and New York exceeded Michigan in the rate of increase in foreign-born residents between 1910 and 1930. The newcomers included sizable numbers of Canadians, Irish, English, and Scots, but they also included nationalities which hitherto had been represented by only a few. In 1960, there were more Michigan residents of Polish than of any other European stock. Russians, Italians, Hungarians, Jugoslavs, and Greeks came in droves to work in the auto plants until the immigration bars were put up. When the automotive industry shifted to war production in the 1940's and when, after the war it enjoyed a prolonged boom based not only on civilian production but also large defense contracts, the great influx from neighboring states and the South began.
    Most of the people who came to Michigan after 1910 settled in cities. In that year there were only 3 cities in the state with a population of more than 50,000; by 1960, there were 17. The number of cities in the 25,000-50,000 class increased from 6 to 20 in the same period. The growth of cities in this period has been, of course, characteristic of the whole country, but it proceeded more rapidly in Michigan than in most other states.
    Adjustment to the urban frontier was still incomplete when the movement outward from the central cities into the suburbs began. This exodus form established urban communities into open country on the fringe was at first residential, but subsequently became commercial and industrial as well. The movement had its origin in the extension of electric street railways beyond city limits in the early 1900's and was accentuated by the electric interurban, which made daily travel into the central city and back to the suburbs practicable. The movement continued after buses replaced the electric trolleys and interurbans, and reached its high point after World War II, when prolonged prosperity enabled almost every family to have one or more automobiles.  In the 1950's, the urban fringe population within urbanized areas in Michigan more than doubled; the proportion of the state's population living in these areas increased from 16% in 1950 to almost 30% in 1960. In the same ten-year period, the proportion living in central cities of over 50,000 dropped from 40% to less than 33%. The first suburbanites were pioneers in many of the same ways as the farmers who came in the 1830's. Land acquisition was a matter of prime importance; transportation was a vital matter; provision for the necessities of life (such as water, supplies, waste disposal, fire protection and police protection in the case of the suburbanite) involved difficult problems; new governmental agencies had to be devised; schools and churches had to be built. And if those who departed from the central cities had problems, so did the central cities themselves: loss of business in the down-town areas, expensive street-widening, freeways, and parking projects to lure the shopper back down-town, the decay of residential areas vacated by those moving to the suburbs and occupied by low-income groups, a declining tax base, and many others.
    The suburban frontier brought a new kind of population distribution. Within the suburbs themselves, the population was predominantly middle-class, white and Republican; within the central cities, unskilled laborers, African-Americans, people of foreign stock, and Democrats were much more numerous. Less than 12% of the non-white population of Michigan in 1960 lived in the urban fringe; almost 80% lived within the central cities.