Flying is complicated - just be sure to factor in the time it takes to get to the airport AND to get to your plane. Security can easily take 30 minutes - even an hour, although that would be a bit unusual.
You will even have to go through security twice if you are flying international, because you have to clear customs on your first landing in the US. In Europe, you never know but it is not uncommon that you have to go through security to change wings at the airport.
Always leave at least 90 minutes is my advice. I have made it on less (60 minutes) but it can be a matter of luck. I have also missed planes due to too short layover times.