The TSA recommends getting to the airport 2 hours before scheduled departure, and I have always stuck to this rule. Airfare is expensive, and the last thing that I want to do is miss a flight because I didn’t get to the airport with enough time to get my boarding pass and get through security.
I have finally come to the conclusion that, at the Louisville International Airport (that officially has no international flights), this is indeed not necessary. Getting your boarding pass (if you don’t check in and print it at home) has never me taken more than 5 minutes. Because this airport is a TSA training airport, there are usually multiple security lanes open, fully staffed, taking less than 20 minutes to get through, even when they have to inspect your bag. There are only 2 terminals, each with about 15 gates, and half of do not seem to be in use (high prices? Airline consolidation?) Even after stopping to get coffee and chat with the baristas, you get to the gate and still have 45 minutes before boarding even starts.
Of course, I have that constant fear of missing my flight, so I am sure that I will always be at the airport 2 hours early.