One of only four U.S. zoos to exhibit giant pandas, the 100-acre San Diego Zoo features 3,700 animals from more than 650 species and subspecies, and the 1,800 Safari Park has another 2,600 animals from 300 species. Some of the zoo's biggest contributions have come through its conservation programs, including its distinction as the first North American zoo to produce a surviving giant panda cub through artificial insemination.
Photo courtesy of Heather Paul

An Association of Zoos and Aquariums award-winner for its exhibits, the Dallas Zoo is the largest in Texas with 106 acres. Founded in 1888, the zoo features approximately 430 species (not including fish), of which 66 are part of the AZA Species Survival Plans. The Wilds of Africa exhibit, where guests embark on a Monorail Safari through six exhibit areas, was the first in the world to include every major habitat on the African continent.
Photo courtesy of DCVB

Chicago's 216-acre Brookfield Zoo, operated by the Chicago Zoological Society, features all the favorites. Guests find polar bears, tigers, gorillas and other iconic critters, as well as a few interesting residents, like a spirited flock of Humboldt penguins with its own baby chick born in February. The Brookfield Zoo has also been recognized by the Association of Zoos and Aquariums for its outstanding educational programs, including the partially kid-designed Hamill Family Play Zoo.
Photo courtesy of Michael (a.k.a. moik) McCullough

More than 6,000 critters reside at the 55-acre Houston Zoo, its exhibit spaces designed to get visitors up-close-and-personal with some of the world's most interesting species. In the indoor Natural Encounters exhibit, for example, young visitors can crawl through a transparent tunnel to see a piranha habitat from the inside. "Meet the Keeper" talks give guests a behind-the-scenes look at how zookeepers keep the animals happy and healthy.
Photo courtesy of Greater Houston Convention and Visitors Bureau

Omaha's 161-acre Henry Doorly Zoo features an aquarium, IMAX theater and a drivable or hike-able wildlife safari park. Notable exhibits include the Desert Dome, the world's largest indoor desert environment, and the Lied Jungle, the country's largest indoor rainforest. The zoo's Center for Conservation and Research addresses a variety of global conservation issues in cooperation with other such facilities.
Photo courtesy of Omaha Convention & Visitors Bureau

At 580 acres, the Columbus Zoo & Aquarium is the largest of our 20 nominees and has been recognized by the Association of Zoos and Aquarims for both its exhibits and its conservation efforts. Some 575 species from around the world are represented, and the zoo contributes more than $1 million annually to over 70 projects around the globe. Jack Hanna, America's most famous zookeeper, serves as the director emeritus of the Columbus Zoo.
Photo courtesy of S Pisharam

More than 3,500 animals call the 70-acre Memphis Zoo home, with some 500 different species represented. Perhaps its most famous denizens are the pair of giant pandas, Ya Ya and Le Le, who live in the three-acre CHINA facility; it's one of only four zoos in the nation to exhibit these animals. Tennessee residents can visit the zoo free of charge on Tuesdays after 2 pm.
Photo courtesy of Karen Dorsett

One of the oldest zoos in the country, the 79-acre Cincinnati Zoo houses some 580 animal species, with another 3,000 plant varieties in its botanical gardens. The zoo is no stranger to "Best Zoo" lists, thanks in part to programs like Nocturnal Adventures, where families can pitch a tent and camp out in the zoo, and exhibits like the Spaulding Children's Zoo, complete with an animal nursery where visitors can peek in on the zoo's newest babies.
Photo courtesy of Cincinnati USA Convention & Visitors Bureau

The 90-acre St. Louis Zoo exhibits 600 species of animals representing every continent and major biome on the planet. It's also our only nominee to offer free entry, though some exhibits and shows charge smaller admission fees. The zoo's Penguin & Puffin Coast exhibit is one of the best penguin habitats in the country, with four species of penguins and two species of puffins on display.
Photo courtesy of David Merritt/St. Louis Zoo

With 9,000 animals representing more than 800 species on display, the Toledo Zoo is one of the most complete zoos in the world. Highlights include the Hippoquariam, where visitors can observe hippos both above and below the water, and Nature's Neighborhood, the Toledo Zoo's award-winning children's zoo.
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