The “Mitchell Map” from the late 1700s was the basis for drawing the boundary between the Michigan Territory and the state of Ohio. Inaccurate map-making lay at the heart of the dispute over the Toledo Strip.
Michigan gave away the Toledo Strip in exchange for the Upper Peninsula at a Dec. 14, 1836 meeting dubbed the Frostbitten Convention.
The deal, which ended the Toledo War that Michigan waged against Ohio, was brokered on a freezing day at the original Washtenaw County courthouse, thus the phrase “Frostbitten Convention”.
For the full article, see “Michigan history: Toledo Strip is given up for U.P.”, Detroit Free Press, December 12, 2010.
Additional reading:
The Toledo War : the first Michigan-Ohio rivalry
Toledo War wikipedia entry.
Toledo War entry courtesy of the Michigan Department of Military and Veteran Affairs.
Also see Pasty Central Day in History : December 14, 1836
Emily Bingham, “Best deal ever: 180 years ago, Michigan lost Toledo, got the U.P.“, MLive, December 14, 2016; updated February 20, 2017.