What percentage of the US is owned by the Federal Government?

Federal lands are lands in the United States for which ownership is claimed by the U.S. federal government, pursuant to Article Four, section 3, clause 2 of the United States Constitution.The United States Supreme Court has repeatedly held that this section empowers Congress to retain federal lands, to regulate federal lands such as by limiting cattle grazing, and to sell such lands. As of March 2012, out of the 2.27 billion acres in the country, about 28% of the total was owned by the Federal government according to the Interior Department. The United States Supreme Court has upheld the broad powers of the federal government to deal with federal lands, for example having unanimously held in Kleppe v. New Mexico that "the complete power that Congress has over federal lands under this clause necessarily includes the power to regulate and protect wildlife living there, state law notwithstanding."