Illinois

Yes, but you have to follow a couple of procedures. The state of Illinois does not allow carry of a handgun, so it has to be unloaded and inaccessible. The best way to do it is to have it in a locked case, unloaded, in the trunk, with the ammo completely separate. However, the city of Chicago has a ban on guns, and as far as I know, they have not repealed it even with the Supreme Court ruling, so you can't take a gun to Chicago.

AJG1945 Edit

The City of Chicago's law does not go quite as far as the above answer suggests. The Chicago Municipal Code Chapter 8-20 states:

8-20-010 Unlawful to carry -- Exceptions.

It shall be unlawful for any person to carry or maintain in any vehicle or about his or her person except when on his or her property or in his or her residence or fixed place of business, any rifle, shotgun, or other firearm; provided, that this section shall not apply to:

* * *

(10) Transportation of weapons broken down in a nonfunctioning state.

Chapter 8-24 states:

8-24-020 Carrying dangerous weapons.

* * *

(e) No person shall carry concealed on or about his person a pistol, revolver, derringer or other firearm... (followed by several not generally applicable exceptions).

Finally, the City of Chicago requires registration of firearms (and I believe this is where the idea that you can't have a firearm in the City comes from), but the applicable ordinance provides:

8-20-040 Registration of firearms. (a) All firearms in the City of Chicago shall be registered in accordance with the provisions of this chapter. It shall be the duty of a person owning or possessing a firearm to cause such firearm to be registered. No person shall within the City of Chicago, possess, harbor, have under his control, transfer, offer for sale, sell, give, deliver, or accept any firearm unless such person is the holder of a valid registration certificate for such firearm. No person shall, within the City of Chicago, possess, harbor, have under his control, transfer, offer for sale, sell, give, deliver, or accept any firearm which is unregisterable under the provisions of this chapter.

(b) This section shall not apply to:

(5) Any nonresident of the City of Chicago participating in any lawful recreational firearm-related activity in the city, or on his way to or from such activity in another jurisdiction; provided, that such weapon shall be unloaded and securely wrapped and that his possession or control of such firearm is lawful in the jurisdiction in which he resides;

Thus, it appears that transport of a gun through Chicago is permitted, so long as the firearm is not carried concealed and, pursuant to Illinois Statutes ILCS 5/24-1, is broken down in a non-functioning state, or is not immediately accessible or is unloaded and in a case, firearm carrying box, shipping box or other container by a person who has been issued a valid FOID. If you are not a resident of the city, the firearm need not be registered if you are going to a "lawful firearm-related recreational activity." You should probably commit those words to memory in case you are ever asked.

I have heard from a number of sources that they regularly transport firearms for shipment in checked baggage to O'Hare and Midway airports (both within the confines of the City of Chicago). See, for example, comments at http://sigforum.com/eve/forums/a/tpc/f/320601935/m/760101641/p/1

Despite many anecdotal stories about the horrors of even thinking about a gun within the city of Chicago, I have never actually talked to anyone who has had any problem with transporting a gun as discussed above.

In short, break it down, lock it up, and don't stop within the City unless you are transporting to the Airport, in which case you should limit your stop to your arrival at the Airport.

The last time I travelled through Illinois, I was told I was ok as long as I didn't go through Chicago at any time. However, calling the local police department or state department is notorious for getting incorrect information because the person you speak to may not be a police officer, or may not be familiar with the law and may be just giving you his or her opinion.

Update:

Just to update on this post, I checked a handgun yesterday with Southwest Airlines from Chicago Midway Airport to Philadelphia. The gun was in a hard sided case as required and it was disassembled. I had no problem with Southwest, other than that they were obviously annoyed that I was slowing down progress on a busy evening. Put the certification in with the gun, locked the box and carried my baggage to TSA. TSA seemed delighted to have something to break up the boredom of what was obviously a slow evening for them. Checked the bag. Had me open the locked hard case to check the gun again and relock it and close and lock the suitcase. No problems and I was on my way home.