Chicago: this is more complex, one should line up for the immigration interview first, then pick up the checked luggage (it may wait for a little long time). And, there’s an airline luggage checking center right after you walk out the luggage pickup place, one can simply hand the luggage to them without any other document checking. Then, leave terminal 5 to terminal 1 for national airline by taking an airport train. There’s one luggage security check before you find your gate for the last flight. However, after this check, all you have to do is sit down and wait, like what I am doing now.