Michigan was one of the most important states in the development of the American automotive industry. Starting in the turn of the century, it was host to some of the first major automobile factories, including Ford and Olds (which made Oldsmobiles). This created great wealth and opportunity in the state, attracting people from around the country and many immigrants from foreign nations. This made cities like Detroit a melting pot.
Michigan further established itself at an industrial powerhouse during WWII, when its industrial capacity was used to support the war effort. During this time, FDR pushed legislation that legalized unions, which led to the unionization of many industry-based jobs and established an almost 100% tendency in Michigan to vote democrat, which has continued to this day (excluding the 2016 election).
The heavy industrialization in Michigan also set it up for some rough decades in the 1970s and beyond, when international competition caused many to lose their automotive and other manufacturing jobs. This has actually set Michigan up for a very difficult situation, with cities like Detroit losing many thousands of jobs over the years and becoming a shell of what they were.
