Asarco LLC (Asarco) owned and operated a mining complex in Arizona and sought to expand its operations. Asarco proposed a land exchange with the Bureau of Land Management (BLM) (defendant), under which Asarco would receive 10,976 acres of public land in exchange for 7,300 acres of Asarco’s private land. Under the Mining Law of 1872 (Mining Law), 30 U.S.C. §§ 21-54, Asarco already held mining and mill-site claims to some of the public land. The Mining Law required Asarco to submit Mining Plans of Operations (MPOs) to the BLM prior to mining on the public land. The MPO process required the BLM to comply with certain laws, including the National Environmental Policy Act (NEPA), 42 U.S.C. § 4321 et seq., and the Federal Land Policy and Management Act (FLPMA), 43 U.S.C. § 1701 et seq. The BLM prepared an environmental impact statement (EIS) under NEPA. The EIS concluded that all foreseeable uses of the public land were mining-related and that mining was expected to occur under all alternatives, including the no-action alternative. The BLM also issued a Record of Decision (ROD) that listed no disadvantages and several advantages to the land exchange, including better facilitation of land management and mining-activity support. The ROD concluded that the public interest would not be harmed, because mining would occur on the public land in the same manner regardless of whether the exchange occurred. The Center for Biological Diversity and other conservation groups (plaintiffs) filed suit against the BLM in federal district court. The district court granted summary judgment for the BLM, upholding the exchange. The plaintiffs appealed.