I don’t recommend doing that, since it would mean booking separate tickets and that can get bad when you miss a connection. 90 minutes from international to domestic at ORD
can be cutting it a bit close. It takes time to clear customs and immigration. You'll have to recheck luggage and then catch the train to terminal three and clear security. For comparison's sake, I arrived at the parking lot at ORD
60 minutes for a flight, checked no luggage and already had a boarding pass and used priority security, but still came close to missing the cutoff for my flight. By the time you leave the international terminal, you'll have 60 minutes if everything is going well, but if not, you'll be stuck.
Also about the UA
/EI connection, that one is better, but you have to take the train from T1 to T5
, and even though November isn't the worst month, you'll be travelling on a busy weekend before Thanksgiving. Those short flights in and out of ORD
can get really delayed. 1 hour delay is very common, and if you are delayed an hour, you have missed your flight since check in cutoff for international is usually 60 minutes before a flight.
Now it would be different if you were flying a single airline. That would be fine, but rechecking in and transfering terminals will be a mess. And worst of all if there are delays, airlines will not be helping you since it won't be their fault since you are on multiple itineraries and you might have to pay a lot if you miss a flight.
I recommend at least two hours if you are going between domestic and international especially late in the day and if you are switching airlines. Domestic to International connections are typically easy, but domestic flights at ORD
late in the day get delayed a lot, and international flights tend to remain on time. International to domestic is bad since you have to clear immigration and customs and all international flights arrive in terminal 5 and domestic flights leave from T1-T5. It takes 10-15 minutes to get between T1 and T5
. It is a decently long train ride and the trains leave only 4-6 minutes apart.
If you have never designed an airplane part before, let the real designers do the work!