America's Most Visited Zoos

#4 Columbus

#15 Cincinnati

The Methodology: We sourced our data from the Association of Zoos and Aquariums (AZA), which tracks annual attendance rates at accredited zoos in America (all major zoos are accredited). Attendance figures were reported by individual zoos. We used the numbers from 2010, the latest year for which comprehensive data were available. We did not include theme parks because they do not publicly report attendance rates and they have world-class thrill rides that are big draws in attracting visitors. (Had we chosen to include them, Disney’s Animal Kingdom would have been No. 1 and Busch Gardens Tampa Bay would have been No. 2, with respectively 9,686,000 and 4,200,000 annual guests.) Since our focus was on traditional zoos, we chose not to include aquariums, a category of their own. However, we did not exclude zoos that had an aquarium on their premises as part of the entire zoo.

http://www.travelandleisure.com/articles/americas-most-visited-zoos