In 1871, at Jacob Davis's tailor shop, the riveted work pants now called blue jeans were invented. Jacob Davis made heavy-duty work pants out of sturdy cotton duck fabric he obtained from the San Francisco wholesale firm of Levi Strauss & Co. To strengthen his pants, Davis developed the idea of placing copper rivets at the stress points. Needing a business partner, he approached Levi Strauss, and on May 20, 1873, the two businessmen received Patent #139,121. They soon began manufacturing copper-riveted work pants out of blue denim, and Levi's Jeans was born as an American fashion icon.