How Michigan and Ohio Got Part of Their Shapes: The Toledo War
The Toledo War was a boundary dispute between the State of Ohio and Michigan Territory over the area known as the "Toledo Strip". It emanated from a poor understanding of the location of the Great Lakes, and vague interpretations of the border between Ohio and Michigan. The area shaded in pink is the land in question.
Image: Map by David Burr from U.S. House Report 380, 24th Congress, 1st Session, highlighting the contested land area between Michigan and Ohio territories (Wikipedia Commons)
The "Mitchell Map" of the region, from the late 18th century, used to create the Ordinance Line of 1787. The southern tip of Lake Michigan is depicted as being farther north than Lake Erie.
The "war" did not result in any deaths in either state, but skirmishes and uprisings on each side did occur. Nonetheless, the episode ended in 1837 when, in exchange for dropping the claim to the Toledo Strip, the State of Michigan was admitted to the United States as the 26th State. In return, it gained possession of the Upper Peninsula. Thought to be mostly worthless at the time, the UP became an invaluable resource for copper mining and timber. Michigan may have lost the battle to keep Toledo in the boundaries of its state, but ultimately I would say they easily won the war over time.
One interesting quirk about the result is that there is now an exclave of the State of Michigan known as "Lost Peninsula" that is only accessible on land through Ohio.
Further Reading: "The Toledo War: The First Michigan-Ohio Rivalry" by Don Faber
Thanks as always for reading!