Unfortunately the majority of the USA, even where people don't live, is valuable private property one way or another. Back when there were fewer people and especially agriculture was much more manual labor intensive, it simply wasn't possible to work every last bit of land, so building new houses at the edge of town was not generally a huge problem (not that people didn't care about ownership, of course, but they cared less - i.e. it was cheaper). Today it is, since every bit of land you build houses on means removing that land from some other economic purpose.