As a Wisconsin born and raised (born in Green Bay, grew up 30-45 min north of Milwaukee) translplant (immigrant?) to Chicago, I can probably shed a little light on the FIB think. It's not anything like the NYC-Chicago resentment as has been suggested above.
The FIB thing is deep seeded resentment that has developed as a result of the disrespectful behavior of Illinois natives while in our state. This is most obviously demonstrated by the fact that practically everyone in Wisconsin drives 5-7 MPH over the speed limit and gets pissed when some douchebag from Illinois in a BMW is riding their tail because they are in the left lane and only passing prople going 3 or 4 mph slower than them instead of going 90 MPH in a 65 MPH zone.
There is also a perception that people from Illinois come to our state for the weekend and make a mess (litter, get drunk, piss on everything, impregnant our women, whatever) because they are just going home in a day or two anyhow.
A lot of it also comes from the fact that, as we build more and more freeways into the state's hinterlands, the FIB's pour in and scoop up all the lakefront properties that used to be exclusively the territory of Wisconsin families because it used to take 8 hours to get there from Chicago and now only takes 4 hours. Property values on Wisconsin lakes and rivers have soared south of an East-West line starting at Green Bay and crossing the state. I'm convinced this is because almost all the freeways end at approximately that line. This is something we've brought upon ourselves and, I suppose, also something that is necessary for the state's progress. Shocking as it is, there was no 4 lane freeways between Milwaukee and Green Bay or Appleton when I was a kid. I remember them building US-41 and compeleting I-43. They just recently completed the first 4-lane route from Green Bay to Minneapolis (US-10) a few years ago.
But Wisconsinites in general view people from Illinois as disrespectful of our state, resources, and way of life. It's not like Chicago-NYC where Chicago is tired of being considered second best, Wisconsinites have absolutely zero desire to be anything like Chicago at all and take pride in being a slower paced place to live where your hobbies include things like fishing, watching the Packers, and drinking beer. There is no desire to have a taller building or a fancier Art Museum (though Milwaukee did knock that one out of the park), there is only a desire to be left alone by that obnoxious dick who just blew by you in an Illinois plated Escalade pulling a $300k cigarette boat who is going to drive that boat through every slow-no-wake zone pulling a 3 foot wake and trashing all the shorelines we've poured millions into preserving and restoring.
Originally Posted by the urban politician
Slowly but surely, Milwaukee will catch on.
Cities change, and I think Milwaukee will evolve into its own. What's holding Milwaukee back is the State in which it's in. Wisconsin blows.
You blow, Wisconsin is awesome, it's not our fault you chose to move to the worst part of the state! Wisconsin gets progressively shittier the closer you get to Chicago because all the real Wisconsinites move as far away from Chicago as they can so you get a bunch of sell outs who half ass the Wisconsin lifestyle massing close to the border.