“The world is blue-jean country now,” LIFE proclaimed in its Nov. 24, 1972, issue. At that time, blue jeans were closing in on their 100th birthday, or at least the anniversary of the official patent Levi Strauss and Jacob Davis were granted on May 20, 1873, for copper-riveted jeans. The sturdy cotton trousers had not only become synonymous with American fashion, but they were also a hot second-hand commodity overseas, as Europeans sought to embody what LIFE called “the aura of Wild Western authenticity.”
Blue jeans as we know them today were a collaboration between Davis, a tailor, and Strauss, a businessman. Davis had first constructed the strong working pants for a customer, using copper rivets to reinforce the seams and pockets. Within a couple of years, unable to meet skyrocketing demand for the durable garment, he approached Strauss for both financial support and a proposed partnership to work toward a patent.
When LIFE revisited Davis and Strauss’ invention in the early 1970s, the U.S. was producing 450 million yards of denim annually and American jeans were selling on the Russian black market for $90. LIFE described this “denim takeover” as follows:
The jeans that once encased the scrawny rumps of cowboys and gold miners of the American West have become the standard garb of the world’s youth. They’re the favorite off-duty clothes of fashion models from L.A. to St. Tropez. By buying up bales of fashionably used ones, Britain and the Continent have made millionaire exporters of U.S. ragmen.
The biggest irony in blue jeans’ emergence as a worldwide sartorial phenomenon was how far they had come from their original purpose as the laborer’s uniform. “The idea that he might one day be hailed as a world fashion leader,” LIFE wrote, “would surely have given old Levi Strauss a laugh.”
Liz Ronk, who edited this gallery, is the Photo Editor for LIFE.com. Follow her on Twitter at @LizabethRonk.