um... because they purchased it in the Louisiana Purchase and never let anyone homestead it and instead decided to keep it.
The federal government actually owns most of the land in the west
here’s a link to a map off all the land the government still owns:
http://kalipinckney.files.wordpress.com/2012/02/all_us_public_lands.jpg
I’ve often wondered why they still own so much myself, but as long as they do, they are free to do with it what they want in my opinion.
(if it were up to me, i’d sell almost all of it and pay off the national debt)
