What annual date does Levi's 501 Day celebrate?

Levi's 501 Day is celebrated annually on May 20.

The date commemorates the 1873 patent associated with Levi Strauss and tailor Jacob Davis's riveted clothing design. That patent is central to the history of the 501 because the rivets helped reinforce points of strain on work trousers. Levi's uses 501 Day as a yearly celebration of the model's heritage and global cultural reach.

The celebration is sometimes confused with the date the 501 model number was introduced. Those are different historical milestones. May 20 refers to the patent anniversary, while the 501 name and product evolution developed through later changes in the company's labeling and catalog history.