This is an incomplete list of existing, reputable zoos in the United States. For a list of aquaria, see List of aquaria in the United States, and for a list of nature centers, see List of nature centers in the United States.
Zoos are primarily terrestrial facilities where animals are held in enclosures and displayed to the public for education and entertainment. Animals may be bred, as well, to maintain captive populations and kept under veterinary care. These facilities include zoos, safari parks, animal theme parks, aviaries, butterfly zoos, reptile centers, and petting zoos, as well as wildlife sanctuaries and nature reserves where visitors are allowed. Zoos in the United States show great diversity in both size and collection. Many are notable for ongoing global wildlife conservation and captive breeding efforts, especially for endangered animal species.