Frontier's seating option will be offered on flights departing May 8 through August 31, with 18 "More Room" seats available on each flight, though there are anywhere from 26 to 41 rows on the carrier's aircraft. Tickets start at $39 per passenger.
And though most flights aren't full, major US airlines have boosted their safety measures for their remaining customers.
For most of the airlines, that means requiring masks. Frontier, Delta, American and JetBlue have all made masks mandatory for passengers while they're aboard, and they're recommended at most gates.
Many of those same airlines are cutting their flight capacity in half, too. And on Alaska Airlines flights, passengers can cancel or reschedule their flight if they can't find a seat that allows them proper social distance.