Some nights when I have trouble sleeping I think about the most off-the-wall things, like what happens when all these skanky-looking kids who are in middle school right now start reproducing at a rapid rate and we run out of room... Funny that I just thought that because there is this new map that shows we are free to reproduce all we want, because there is plenty of room! 

Without getting too in depth, the map created by mapsbynik shows (with green shading) everywhere in the US that not a single soul lives. The site explains:

Block is the smallest area unit used by the U.S. Census Bureau for tabulating statistics. As of the 2010 census, the United States consists of 11,078,300 Census Blocks. Of them, 4,871,270 blocks totaling 4.61 million square kilometers were reported to have no population living inside them.

And although the map doesn't have lines to show individual states, you can probably make a pretty good guess as to where Colorado is, and it looks pretty dang green!

According to the map 47% of the US is unoccupied.