Rattlesnake round-ups, also known as rattlesnake rodeos, are annual events common in the rural Midwest and Southern United States, where the primary attractions are captured wild rattlesnakes which are sold, displayed, killed for food or animal products or released back into the wild. Rattlesnake round-ups originated in the first half of the 20th century for adventure and excitement, as well as to achieve local extirpation of perceived pest species. Typically a round-up will also include trade stalls, food, rides, and other features associated with fairs, as well as snake shows that provide information on rattlesnake biology, identification, and safety. To date, round-ups where snakes are killed take place in Alabama, Georgia, Oklahoma, and Texas, with largest events in Texas and Oklahoma. Many round-ups are no longer slaughtering snakes, but have transitioned to educational festivals celebrating rattlesnakes and other wildlife. All round-ups in Pennsylvania return snakes to the wild and two former round-ups in Georgia and Florida use captive animals for their festivals. The largest rattlesnake round-up in the United States is held in Sweetwater, Texas. Held annually in mid-March since 1958, the event currently attracts approximately 30,000 visitors per year and in 2006 each annual round-up was said to result in the capture of 1% of the state's rattlesnake population, but there are no data or studies to support this claim.