I am planning a trip for 2019, and the absolute best result on all points (price, duration, hours of departure/arrival) means taking an international plane landing at Chicago O'Hare only to get 1.5 hour later another one leaving out of the USA.
I am wondering if this amount of time is enough or if I should just choose an alternate route.
I often used the Miami airport in the past for similar cases, and I know that at this airpost it is safer to count at least 2 hours to pass immigration and customs, due to various factors. I am not an US citizen, but will have an ESTA (a new one, my current one will expire before this new journey).
I am really hoping that maybe things could be better at Chicago O'Hare airport, which I never visited yet.
The page at https://www.flychicago.com/ohare/myflight/international/pages/default.aspx does say: "There are many factors that impact how long it may take travelers to complete the immigration and CBP process, but on average it takes no more than two hours.", so 1.5 hour seems risky.
I may even need to change terminals, as http://www.flychicago.com/ohare/myflight/airlines/pages/default.aspx is not completely clear to me: I would arrive with United Airlines on an international flight (so that should be Terminal 5), but I leave with an ANA flight, and it seems Terminal 5 is only for arrivals, so ANA would take off from Terminal 1 I think, which is confirmed in fact if I check there: https://fr.flightaware.com/live/flight/UAL7911 (which also shows that at least recently this flight leaves with 1 hour of delay or even more, which would help me but I can not count on it).
The itinerary will be bought as one (the bags should be checked through but based on previous link, I may need to collect them nevertheless - which is not the case when through Miami), so I know that if the connection is missed I would be rebooked to another flight or the day after, but that would really diminish the usefulness of this choice, so if it is almost guaranteed that 1.5 hour is not enough for transit, I may book something else.
The next best choice involves instead a change at Houston Georges Bush Intercontinental (and I could choose either 1h40, 2h50, 3h50 or 5h10 for my layover time there) and then Los Angeles International before the final flight out of the US. But this makes the whole journey 7 hours longer than through Chicago.