How Illinois got it's Shape
The Illinois Territory’s northern boundary originally ended at the southernmost point of Lake Michigan, leaving it with no port on the Great Lakes, and, crucially, no access to the proposed Erie Canal. Congress shifted the border north, taking land from Wisconsin, and giving Chicago to Illinois. The Mississippi River played a big roll too. Because they could ship stuff all the way down to Louisiana. The state is so long because it needed to reach lake Michigan to be connected to the union.