On June 30, 1805, the first governor of the territory of Michigan was appointed. William Hull, a Massachusetts native, was appointed to govern the state out of the new capital in Detroit.
Although the British lost the Revolutionary War and the fledgling country was handed over to the upstart Americans, the British hung onto Detroit and Mackinac Island for 13 years. It was not until 1796 that conflicts between the British and the French in Europe persuaded the British to relinquish the Michigan forts.
The territory was turned over to the Americans by September 1796. The name of Michigan was first attached to the region in 1805, although as a political unit it looked somewhat different than it does today, containing more land in the south and very little of the Upper Peninsula.
Source: Michigan Every Day