The Ringling Brothers and Barnum & Bailey Circus, which was founded in 1871, put on the final performance of the "The Greatest Show on Earth" Sunday night (May 21). The circus was a staple of American life, traveling all over the country, in big cities and small towns, for 146 years.

"From the bottom of our hearts we want to say thank you all very much," company CEO Kenneth Feld said to the crowd in Long Island, New York, prior to the show. "And please enjoy and celebrate the Greatest Show on Earth one last time."

The reasons for its closing are varied. Declining sales, higher operating costs and waning audience interest certainly played a part, but the circus's ongoing battle with animal-rights activists may have been most significant. PETA had publicly complained for decades about the circus's treatment of its animals, insisting that forcing them to perform was cruel.

Members of the show disagreed with this characterization. Alexander Lacey, who trained the show's big cats, addressed the crowd during the final show. "People are not really concerned with wildlife until they feel it and see it and enjoy it," he said, "and love it as much as I do, until they’ve seen it with their own eyes. It’s so important that you carry on supporting all those people that do dedicate their lives to these animals. Support good, well-run circuses. Support good, well-run zoos. Support good, well-run public parks that look after these animals."

About a year ago, Ringling Brothers removed elephants from the show at the behest of animal-rights supporters. Ticket tales dropped sharply after that move, a clear indication that the circus was losing the public relations fight.

"There are many other animal circuses as well still touring in the United States," animal-rights activist John DiLeonardo told CBS outside the Nassau Coliseum, site of the last performance. "And we’re coming for all of them if they don’t evolve and go animal-free."

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The Ringling Brothers and Barnum & Bailey Circus may have been the most famous, but there are still plenty of other touring shows -- with clowns and acrobats and fire-breathers and contortionists and, yes, exotic animals. “This is one circus,” said a performer. “Where one curtain closes, another opens.”

At the close of the last show, ringmaster Johnathan Lee Iverson thanked all the performers and the audience, leading everyone in a rendition of "Auld Lang Syne," which is traditionally sung at the end of every tour. He then took a bow, saying, "Keep the circus alive inside you! Thank you very much!"

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