Illinois is similar to New York in that its largest city, in this case, Chicago, sometimes takes all the limelight from the rest of the state. While Chicago is great, the state also has a cost of living that's 4% lower than the national average. The state's total population is 12.6 million, with 2.1 being 65 or older, and the sales tax is set at 6.25%. Now, that's the good.
In terms of things to keep in mind, the state is similar to Pennsylvania in that some suspect it's going to run up against some financial issues in the not-so-distant future.