I have a connection time of 50 min from a domestic flight coming from Albequerque going to Vienna. I am not a US citizen. Would it be enough time for me to catch the connection? I should clear customs in Chicago? Thank you very much for your answer!
If you arrive on a domestic flight, you don't need to clear customs or immigration. Your luggage should also be checked through already (if both segments are booked on one ticket obviously). What could be a problem, if your international flight departs from a different terminal (e.g. if it departs from terminal 5 and your domestic flight arrives in 1). But again, if everything is booked on one ticket, the airline is responsible for rebooking you onto the next possible flight, if you should miss your original flight).
If you have booked two separate tickets, then i guess that's already a guarantee to miss your international flight.
If you have just one ticket, all you need to do is get off one flight and onto the next one. Your bags will be checked through and you don't need to go through security again. Things will get tight if your incoming flight is delayed at all or if you have to get a long way across the airport. However, each airport works out minimum connection times and airlines don't sell tickets that require faster connections than that. If you miss the connection on a single ticket, the airline will put you on the next available flight.
If you are on two separate tickets, then this connection is impossible. Check-in for the flight to Vienna will close an hour before departure, and you won't even have landed by then. The airline for the international flight would be entitled to say "Tough luck: you were supposed to get yourself to the airport with enough time to check in but you didn't"; they might book you onto a later flight, they might make you buy a whole new ticket, or they might charge you a fee to change your existing ticket to a new flight.