The new generation of fuel efficient aircraft can move passengers long distances for very little fuel.
The numbers vary wildly, but an older 737-200 got about 65 miles per gallon/passenger in "cattle car" configuration. The -800 gets about 110 MPG/P.
While average loads are around 80% now, and many aircraft have a first class section, and "comfort section", the numbers are as low as 75 MPG/P.
Still, that's exceptional considering a few "forgotten facts". Aircraft travel about 25% fewer miles than driving (on average) . As aircraft travel a much more direct route. And, that aircraft don't have to navigate around large lakes, tall mountains, large sections of "off limits" land areas and so on.
The best way to look at it is that a 737-800 can typically get a passenger from Florida to NY for about 10 gallons of fuel.