Grant signed the Yellowstone National Park Protection Act on March 1, 1872, which declared the park was ?hereby reserved and withdrawn from settlement, occupancy, or sale under the laws of the United States, and dedicated and set apart as a public park or pleasuring ground for the benefit and enjoyment of the people.?

Yes, Yellowstone National Park is federally owned and managed by the United States government. Specifically, it falls under the jurisdiction of the U.S. Department of the Interior and is administered by the National Park Service (NPS). Established in 1872 as the world's first national park, Yellowstone was carved out of federal lands in the territories of Wyoming, Montana, and Idaho. Because it is federal land, it is not "owned" by the individual states, and the laws governing the park are federal statutes. The park's management is funded by the U.S. Congress, and all land within the park boundaries—over 2.2 million acres—is held in public trust for the "benefit and enjoyment of the people." While some private "inholdings" or concessions exist within the park for services like hotels and restaurants, the land itself remains the property of the American public, protected by the NPS from private development and industrial extraction to preserve its unique geothermal features and world-class wildlife habitats for future generations.