1, now register as a member on the website, so that you can accumulate mileage from the first ticket.

Then you can book tickets directly on the website and pay by credit card.

This is the case in America. The first stop of entry, that is, a port city like Chicago, requires entry formalities, and luggage needs to be picked up by yourself. Then re-check the flights behind.

An hour and a half may be too late when there are many people, but don't worry. After entering the country, you can check in for any late flight as long as there are seats left. No charge.