Michigan is the 26th state of the United States on the upper midwest bordering four of the Great Lakes, including the one after which it's named. The state is bordered by Ohio and Indiana to the south, Wisconsin to the southwest, and the Canadian providence of Ontario to the east. Lansing is the capital and Detroit is the largest city.
Wilberforce only includes the southern portion of Michigan. The Upper Peninsula is part of New Guernsey in the Georges' timeline, along with OTLWisconsin and Minnesota east of the Mississippi River. These names are given only on the frontispiece map; in the novel, the province remains unnamed.