I hadn't realized that Wisconsin had once laid claim to Chicago.
You can see the 2 different Illinois-Wisconsin boundary lines here. Under the Ordinance of 1787 Chicago would have been included in Wisconsin.
The city was reportedly founded in 1779 by Jean Baptiste Pointe du Sable. At that point, it was nominally owned by the British, as far as I can make out.
And up until 1786, Connecticut seems to have maintained a claim on Chicago. Think of it - Chicago, CT!
But Congress changed its mind.
And so, today, we find,
Chicago is deployed
firmly in Illinois.