Every day, hundreds of thousands of fliers make — or attempt to make — their connecting flights en route to their final destination.

But what constitutes a reasonable — perhaps even a physically possible — connection time at airports?

What’s considered a legal connecting time — in some cases just 33 minutes — doesn’t mean either you or your bags will make the onward flight.

An analysis of the 25 most connected airports in the U.S. reveals which require the most time to make those flights.

The airport requiring the most time? Houston Intercontinental, at 2 hours and 17 minutes, followed by Dallas, JFK, Atlanta, Denver, Chicago, and Charlotte.

The airports requiring the least amount of time for layovers include Reagan National in Washington, D.C., at just 50 minutes. Chicago Midway and Dallas Love Field are both under an hour, followed by Honolulu, Detroit, Minneapolis, and Baltimore.