Michigan doesn't have any idiosyncratic holidays. The most holidays are observed by the state government, fewer by business in general, and the least by retailing in general.
Jan 1; New Year's Day (gov/bus/retail)
Jan, 3rd Monday; Martin Luther King Jr Day (gov)
Feb, 3rd Monday; President's Day (gov)
May, 4th Monday; Memorial Day (gov/bus)
July 4; Independence Day (gov/bus/retail)
Sep, 1st Monday; Labor Day (gov/bus)
Nov, Monday nearest 11th; Veterans' Day (gov)
Nov, 4th Thursday; Thanksgiving Day (gov/bus/retail)
Nov, day after Thanksgiving Day (gov)
December 24, Christmas Eve (gov)
December 25, Christmas Day (gov/bus/retail)
December 31, New Year's Eve (gov)
We used to have Columbus Day, but it was repealed when MLK Day was instituted.