The history of denim in America dates back to the 1840s, when the durability of the warp-faced, twill textile was a proven choice for workwear clothing, with pants and overalls much in demand. The blue threads of woven cotton were dyed with indigo through a process known as “rope dying” or “chain dying,” while the weft threads were left white and visible only on the reverse side. Over time, other weights of denim were made available, along with different colors: tan, black, and gray. For laborers in the fields, coal mines, forests, and mills, denim was an inexpensive clothing option that was widely available and came in all sizes. During the California Gold Rush of 1848 to 1855, the prospector dressed in his denim work clothing, field jacket, and hip waders was a common sight.