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).

This map details the percentage of state territory owned by the federal government. The top 10 list of states with the highest percentage of federally owned land looks like this:

1. Nevada           84.5%
2. Alaska            69.1%
3. Utah               57.4%
4. Oregon           53.1%
5. Idaho              50.2%
6. Arizona           48.1%
7. California        45.3%
8. Wyoming         42.3%
9. New Mexico     41.8%
10. Colorado          36.6%

 Notable is that all these states are in the West (except Alaska, which strictly speaking is also a western state, albeit northwestern). Also notable is the contrast between the highest and the lowest percentages of federal land ownership.

The US government owns a whopping 84.5% of Nevada, but only a puny 0.4% of Rhode Island and Connecticut. The lowest-percentage states are mainly in the East, but some are also in the Midwest and in the South:

1. Connecticut      0.4%
2. Rhode Island     0.4%
3. Iowa                  0.8%
4. New York          0.8%
5. Maine                1.1%
6. Kansas              1.2%
7. Nebraska           1.4%
8. Alabama            1.6%
9. Ohio                  1.7%
10. Illinois               1.8%

Even the 10^th place is still below the two percent mark. One territory is not specified on the map: Washington D.C. It could be argued that this is the only main administrative division of US territory to be fully owned by the federal government.

Jonathan Leblang and Adam Hahn signaled this map, which appeared as an illustration to ‘Can the West Lead Us To A Better Place?‘, an article in Stanford Magazine.

They are managed by different administrations, such as the (BLM)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.