[PaulDavisThe1st]

Most of that cheap land you are seeing available in the US is not close to what you'd consider farmland.

Consider the location of the 100th meridian as it somewhat bisects the continent. West of that line, you cannot really grow anything without irrigation. East of that line, and to some extent there's enough rainfall that stuff will grow on its own, albeit not optimally.

Most the cheap available land you will find in the US is west of the 100th meridian, and is dry largely inorganic dirt.

As for the cities, you may not be aware of this, but the southwest (and perhaps western) US is in year 21 of a drought that rivals the worst of the last 1200 years, and there is no sign that the situation is likely to improve in the next century or so.

[dreamcompiler]

This. The western half of the US is going to become useless for farming in the next 50 years because all the aquifers are drying up and they take tens of thousands of years to recharge. Which is another way of saying that farming in the western US has only been possible because it harvested fossil water that's now almost gone.

[PaulDavisThe1st]

This is not quite true. Most western US (well, say CA central valley back to the plains) agriculture has been made possible by large scale irrigation systems backed by the construction of substantial reservoirs. From time to time, it has been necessary to pull from groundwater, and from time to time, some farmers have done so even when it wasn't necessary. But in general, most of the agricultural expansion has been based on collected rainwater, distributed via huge systems. This system has worked "well" as long as the snow and the rain has kept coming (and flowing, rather than being absorbed into warm-weather baked soil). But the rain & snow are not making it into the rivers and reservoirs, and so this system has serious problems now.

By contrast, plains and some midwestern ag. has been drawing down the Ogallala aquifer at an insane rate, and that really is "fossil water".

[dreamcompiler]

Correct. I overgeneralized; the coastal western states might be able to continue some farming. Assuming cities like LA don't continue to appropriate more and more water that fell to the ground hundreds of miles away.

[hirundo]

This is the basis of the plot of The Sea of Grass, a classic Spencer Tracy / Katherine Hepburn movie. Tracy is a rancher trying to make this argument to some optimistic farmers. They see it as self-serving, which they are right about, but so is Tracy. Tragedy ensues.