Having recently driven from South Dakota through Wyoming, Montana, Idaho and Washington I am aware of just how much time we spent traversing various national parks, forests, etc. However, my own experiences do not tell the entire story. The following map does a much better job of it.
From the article which is attached to the map, we have this explication:
The United States government has direct ownership of almost 650 million acres of land (2.63 million square kilometers) – nearly 30% of its total territory. These federal lands are used as military bases or testing grounds, nature parks and reserves and indian reservations, or are leased to the private sector for commercial exploitation (e.g. forestry, mining, agriculture). They are managed by different administrations, such as the Bureau of Land Management, the US Forest Service, the US Fish and Wildlife Service, the National Park Service, the Bureau of Indian Affairs, the US Department of Defense, the US Army Corps of Engineers, the US Bureau of Reclamation or the Tennessee Valley Authority.
Among other facts, I did not previously know that Nevada was merely a shell of itself. It is little wonder that Harry Reid is so comfortable in DC–the federal government directly controls 84.5% of his home state.