You can fit the entire world's population into the state of Texas, and it would only be as crowded as the city of San Franciso. That would leave the entire world empty for cultivation etc.
Liberals packed into cities and like to evoke fear that we are running out of space, or sprawl is out of control, but as anyone who has ever flown over this country would notice, there is plenty of open land and cornfields for thousands of miles. There was a movie I guess in the 70's called "standing room only" which was designed to trick people into thinking we will all be packed together "standing room only".