What should I take when I leave Chicago airport for home?

Articles to be carried through the customs:

Passport and I94 form, when boarding in Boston, they have to check your passport and ask for your passport to check in (in my experience, I only say yes, because every time I go back to China, I have to look at my passport when I check in, so they have to do some checks in the system. When you arrive in Chicago, if it is a connecting ticket, you don't have to go through the security check at all, just go to the boarding gate. After arriving at the boarding gate, just give your passport, I-94 form and boarding pass to the staff at the boarding gate counter. They should return my boarding pass and passport, and they should keep the I-94 form. If they don't stay, you must remind them (this kind of mistake is rare. Don't mind anything else.

I have been to Chicago many times, but once, after a woman asked me to fingerprint in front of a machine, the machine gave me an encrypted fingerprint note, but it was useless. This is the only time. If they ask for this, the staff should call me, so just follow the procedure in the first paragraph above. I recently went from new york to Chicago and from Chicago to Shanghai in June.

Interstate 20:

I definitely don't want to go through customs. I've been through the customs for n times, but I haven't checked the entry documents. However, if I return to the United States from China, the original I-20 is absolutely necessary. So take it back to China.