In which year was the patent for copper rivets for denim jeans issued?

Jacob W. Davis (born Jacob Youphes) (1831–1908) was a Latvian-born American tailor who is credited with inventing modern jeans. Growing up in Latvia, he emigrated to the United States as a young man and spent some time in Canada as well. He invented jeans by using sturdy cloth and rivets to strengthen weak points in the seams, and partnered with Levi Strauss to mass produce them.

In December 1870, Davis was asked by a customer to make a pair of strong working pants for her husband who was a woodcutter. To create suitably robust pants for working, he used duck cloth and reinforced the weak points in the seams and pockets with the copper rivets. Such was the success of these pants that word spread throughout the labourers along the railroad. Davis was making these working pants in duck cotton and, as early as 1871, in denim cotton. Before long, he found he could not keep up with demand.

Realising the potential value in his reinforced jeans concept, in 1872, he approached Levi Strauss, who was still his supplier of fabric, and asked for his financial backing in the filing of a patent application. Strauss agreed, and on May 20. 1873, US Patent No. 139,121 for "Improvements in fastening pocket openings" was issued in the name of Jacob W. Davis and Levi Strauss and Company.