On May 1, 1893, President Grover Cleveland opened the World's Columbian Exposition at Chicago, IL. The great fair drew nearly 26 million visitors and had a major impact on architecture, the arts and America's sense of industrial optimism. The many firsts at the fair included the Ferris Wheel, built by George Ferris; the confection of popcorn, peanuts and molasses that became Cracker Jack; and the "clasp locker", a forerunner to the zipper. to commemorate the event, the US Postal Service issued its first picture postcards. The cards became so popular that the Private Mailing Authorization Act was passed in 1898 to allow private manufacturers' cards to mail at the 1 cent rate. Previously, only the official USPS cards could mail at that rate: private postcards cost 2 cents to mail.