I was taught in Real Estate class that the government DOES own the land in the United States. We, the People, only own the right to use it. And that right can be revoked at any time, through the process of condemnation. Typically, the government pays a fair market value (or usually, a bit more) for the land; but they don't really have to. The principles that are involved include "highest, best use of land" and Manifest Destiny. Private land ownership in the U.S. is simply a common misconception.