3. there is no more immigration check-in at O'Hare airport. 4. return the I-94 form (i can't remember exactly the number) to airport staff when you are onboarding leaving Chicago.5. u can bring ur laptop with you. u may need run it in front of security check. usually u only need to get the notebook out of ur bag and let the x-ray machine check it. no too much trouble. 6. O'hare airport is the biggest airport so be sure u walk fast enough to transfer between terminals (there is train to take). suggest u visit the website to get familiar with the map. Good luck and safe trip!

I had experience once, that I had one hour left to connect to another flight in Concourse B. But I went to Concourse C to grab a quick lunch, since there is a food court in C. Then I came back to B and was still able to make couple of phone calls before the agent started to call pre-boarding.

When you fly back from China, however, the plane will park in International terminal and you need to take train to either concourse B or C for your connecting flight. It might take longer.