I'm flying from Cairo to London to Chicago to Minneapolis. Where do I go through US Customs?
First port of entry to US.
US passport control and customs will be in Chicago. If you buy any liquids while transiting the airport in London they will need to go in your checked bag for you flight to Minneapolis.
Make sure you have a 2.5-3 hour layover in Chicago because if you fly into Terminal 5 you have to clear customs then exit the terminal and take a bus to the rest of the terminals and go through TSA security again (which can be very backed up) and then get to your terminal and gate. This is my least favorite airport to return to the USA in.