Freak shows date all the way back to the 16th Century and became quite popular in England. From fire breathers to bearded women, the point was to shock the viewers. One of the earliest examples of a freak show performer would be the conjoined twins, Charles lof Lazarus and Joannes Baptista Colloredo, from Italy. Charles was a fully functioning and handsome man, while his brother was parasitic and hung from Charles' chest. Joannes was a large mass of limbs and Charles often covered him with a cloak when in public.
In the 1800's, PT Barnum often duped his fans with outlandish acts and strange creatures in the U.S. PT Barnum introduced a creature with the head of a monkey and the tail of a fish in 1842. The creatures name was "Feejee" the Mermaid and was owned by an Englishman who claimed to have bought it from Japanese sailors. The englishman then rented it to PT Barnum who created an entire campaign to prove it was a real mermaid. Though Barnum was criticized for exploiting his freaks, he paid them extremely well as well as accomodated every one of them. His most popular act was the "Tattooed Man", George Cententenus.
Over time PT Barnum worked closely with Tom Norman, who exhibited the "Elephant Man". Joseph Merrick aka The Elephant Man, was a young man who suffered from extreme deformitites. Authorities shut down the "Elephant Man" exhibit and Norman earned many Kudos from PT Barnam. As time went on, many felt these freak shows were distasteful, though in the 20th century they slowly became more prominent in the media. In the 1960's a man by the name of Bobby Reynolds created his own side show which included two sbilings half man and half woman.
In 1991, The Jim Rose Circus performed at Lalapalooza, a music festival and immediately gained a large following to his modern day side show. Jim Rose founded his circus sideshow in the early 1990's in Seattle and the side show consisted of The Amazing Mister Lifto, The Enigma, and The Torture King. This modern day sideshow has made TV appearances and was featured in Rolling Stones Magazine.
Today, you'll find freak shows all over the country, http://www.freakshowdeluxe.com is a large group that performs in clubs, fairs and corporate events in Los Angeles.
And if you are a fan of the hit show, "American Horror Story" the creators themed a whole season around a freak show with many references to vintage freak shows.