But when such territories (however acquired) enter into the union and become sovereign states, the land within the new state boundaries should no longer be owned or controlled by the federal government. Constitutionally, the federal government should divest itself at the earliest opportunity of all such lands, except those necessary for the erection of forts, magazines, arsenals, dock-yards, and other needful buildings.
They divested it to try to sell it and make money to run the govt, but they also had to give some of it away to settle the land. Once again, these lands were available up until 1976, but not after that.
Some people say the feds should have done what Spain and Mexico did. Give away huge tracts of land like the de Vaca land grant that was 400,000 acres. Or like the land grants to the railroads. But Congress didn't want to give away large tracts to individuals.