Upon being invented in 1873, the 501 got its official name in 1890, the same year Levi’s patent for riveted clothing expired. To stay ahead of the competition, the brand subsequently began printing the interior of the pocket bag with information regarding the strength and originality of the 501 pant. The style was still referred to as overalls at the time, featuring a cinch back and buttons at the waist that allowed you to attach suspenders. You’ll also notice that there was only a single pocket on the back of the silhouette, as a second wasn’t added until a newer version of the 501 arrived in 1901.