Giraffe at the Phoenix Zoo in Phoenix, Arizona. Opened in 1962, it is the largest privately owned, nonprofit zoo in the United States. The zoo was founded by Robert Maytag, a member of the family that owned a famous appliance company. It displays more than 1,400 animals and contains 2.5 miles of walking trails through four main themed areas. Original image from Carol M. Highsmith’s America, Library of Congress collection.