Turnstile

A turnstile is a form of gate that allows only one person to pass at a time, used to enforce one-way movement, verify a ticket, transit pass, or other form of payment, or provide an accurate count of how many people have passed through an entrance. Turnstiles were originally used to let people through a gap in a fence or wall while keeping livestock out, a use recorded around graveyards, and by the sixteenth century they had appeared on toll roads in London; they became a standard fixture at sports stadiums and swimming pools during the nineteenth century, and in the United States the grocer Clarence Saunders notably installed turnstiles in his Piggly Wiggly stores. Magnetic-strip ticket turnstiles appeared in Tokyo in the late 1960s, and modern versions range from waist-high optical and drop-arm turnstiles to full-height turnstiles roughly seven feet tall built for stronger security, now used in transit stations, airports, amusement parks, factories, and casinos.