As much a part of Americana as apple pie and Amish quilts, the once-humble pair of Levi Strauss jeans isn't so humble anymore.

In fact, the oldest pair known to still exists - made in the 1880s, the decade after they were invented - sold on eBay a few years ago for the staggering record price of $46,532, finding their way back into the archives of the company that manufactured them.

In 2005, a 155-year-old pair of 501s was bought by an anonymous bidder, again on eBay, for $60,000. Though these prices were an extreme, other vintage Levi's are also highly collectible, even those made in the 1950s and '60s.

The saga behind this American icon opens in the California Gold Rush year of 1853, when a 24-year-old Bavarian immigrant named - yes - Levi Strauss arrived in San Francisco by clipper ship via New York, where his two brothers had established a dry goods firm. With a brother-in-law, he opened a little shop on

Strauss often brought a heavily laden packhorse directly into the region's mining areas, and while there he heard the men complaining about the fragility of their cotton "britches." This inspired Levi to construct some more durable work pants for the miners, and he requested his brothers to send an additional supply of heavy cloth.

What they shipped was a thick-twilled cotton fabric from France known as serge de Nimes - a name later condensed to form the word denim. The concept of using rivets in the pants came from a Carson City, Nev., customer of Strauss', a tailor named Jacob Davis, who had the idea of using copper rivets to reinforce the points of strain on trousers, such as pocket corners and the base of the button fly. Davis told his idea to Strauss, and in 1873, they obtained a joint patent for strengthening "a pair of pantaloons" by having their pocket openings secured at each end by rivets.

Straus started manufacturing what he called "waist-high overalls," dyed an indigo blue, and they were immediately successful. In 1890, the initial model to contain a watch pocket was assigned the inventory number "501," by which it is still identified today.

Very little has changed throughout their history, except for the removal of uncomfortable crotch and back-pocket rivets, the addition of belt loops in 1922 and the introduction of zippers in 1955. The iconic leather label showing a pair of jeans being pulled between two horses has survived since 1886; the familiar red Levi's tag sewn into the side of the right-hand back pocket first appeared in 1936 as a means of identifying the brand from a distance.

The term jeans - which Strauss is said to have abhorred - comes from the phrase "bleu de Genes" - the French phrase for the dye of the fabric used in the all-purpose trousers long worn by sailors from Genoa, adapted because they could be worn wet or dry, with their legs rolled up while they swabbed the decks.

It took awhile for Levi's to leave the workplace and become a staple of leisure life. A turning point came when Vogue magazine featured them in 1935, and by the 1940s - known by their other name, dungarees - they were a teenage uniform. In fact, by World War II, they had become so popular that the government declared them an essential commodity, limiting supplies only to defense workers.

After the war, further boosted by Western movies and their use by such stars such as James Dean, Marlon Brando and Elvis Presley, they became an international fact of life.

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Linda Rosenkrantz has edited Auction magazine and authored 15 books, including "The Baby Name Bible" (St. Martin's Press; www.babynamebible.com). She cannot answer letters personally.