Yes-it was tamed by people who were able to migrate here because of the costly and hugely unpopular war with Mexico. The promise of land grants from the federal government, along with the massive public subsidies for developing land and sea lanes to the west, helped to encourage them to move.
Huge pieces of the west, btw, are still state owned.
Yes. THe key part is "huge land grants". You can develop pretty much the most unforgiving bits of soil by giving it for symbolic prices to whoever will develop it.
And yes, huge parts of the west are still state-owned, but IIRC there have been legal challenges to it.