Most of Michigan is in the Eastern Time Zone excepting four counties. These four counties are Gogebic, Iron, Dickinson, and Menominee. These four counties are in the Central Time Zone. Due to daylight savings time the fact that most of Michigan is in the Eastern Time Zone means that most people in Michigan enjoy very long summer days with dayight that lasts until 9 or even 10 pm.
The reasoning for this is simple. The way the timezones used to fall meant that back around the turn of the century the sun was setting around 7pm in July in Detroit. The people wanted to be able to enjoy the summer days more so the timezone was changed to accomodate this.