The largest zoo in the United States is the Henry Doorly Zoo in Omaha, Nebraska. This zoo is home to about 17,000 animals of 962 different species as of 2015. The Henry Doorly Zoo encompasses over 130 acres of land.
In terms of land mass, the Bronx Zoo could be considered the largest zoo in the United States because it comprises 265 acres of park land. However, it pales in comparison to the Henry Doorly Zoo in terms of the number of animals in houses with 4,000 animals of over 650 species. Other large zoos include the San Diego Zoo in California and the Columbus Zoo in Ohio.