Category: Image - :Closeup of copper rivet on jeans.jpg|thumb|250px|Denim as used for blue jeans, with a copper rivet to strengthen the pocket.

Denim is a rugged cotton twill textile, in which the weft passes under two (twi- "double") or more warp fibers. This produces the familiar diagonal ribbing identifiable on the reverse of the fabric, which distinguishes denim from cotton duck. Denim has been in American usage since the late eighteenth century. In 1789 George Washington toured a Beverly, Massachusetts, factory producing machine-woven cotton denim. (Massachusetts Foundation for the Humanities: Mass Moments). The word comes from the name of a sturdy fabric called serge, originally made in Nîmes, France, by the Andre family. Originally called serge de Nîmes, the name was soon shortened to denim. "Levi Strauss had the canvas made into waist overalls. Miners liked the pants, but complained that they tended to chafe. Levi Strauss substituted a twilled cotton cloth from France called "serge de Nimes." The fabric later became known as denim and the pants were nicknamed blue jeans." In French of Nimes or De Nimes shortened to Denim[http://inventors.about.com/od/sstartinventors/a/Levi_Strauss.htm] Denim was traditionally colored blue with indigo dye to make blue "jeans," though "jean" then denoted a different, lighter cotton textile; the contemporary use of jean comes from the French word for Genoa, Italy (Gênes), where the first denim trousers were made.

A similarly woven traditional American cotton textile is the diagonal warp-striped hickory cloth that was once associated with railroadmen's overalls, in which blue or black contrasting with undyed white threads form the woven pattern. Hickory cloth was characterized as being as rugged as hickory wood—not to mention the fact that it was deemed to be worn mainly by "hicks"—although neither may be the origin of that term a nickname for "Richard". Records of a group of New Yorkers headed for the California gold fields in 1849 show that they took along four "hickory shirts" apiece. Hickory cloth would later furnish the material for some "fatigue" pantaloons and shirts in the American Civil War.

The word dungarees, to identify heavy cotton pants such as overalls, can be traced to a thick cotton country-made cloth, Dongari Kapar, which was sold in the quarter contiguous to the Dongari Killa, the fort of what was then known as Bombay (Hobson Johnson Dictionary). The word entered English with just this meaning in 1696 (OED). Dongri Fort was rebuilt in 1769 as Fort George, Bombay, where the first cotton mill was established in 1854. Dyed in indigo, the traditional cloth was used by Portuguese sailors and cut wide so that the legs could be swiftly rolled up when necessary. Thus, dungarees have a separate history.