On Oct. 1, in a remote RV park in northern New Mexico, a pair of excavated Levi’s jeans from the 1880s sold at auction for $76,000. The buyer? A 23-year-old from San Diego.

“I’m still kind of bewildered, just surprised in myself for even purchasing them,” said Kyle Haupert, who walked away with the jeans, during an interview a few days after the auction closed. 

The bid makes the pair of vintage jeans one of the priciest ever sold. Mr. Haupert, a vintage clothing dealer, put up 90 percent of the winning bid, while the remaining 10 was kicked in by Zip Stevenson, an elder statesman of the vintage market who has run the Los Angeles shop Denim Doctors since 1994. 

Including the buyer’s premium, the pair paid $87,400 total for the jeans.

The high-value Levi’s are an extraordinarily rare pair of jeans from an era before planes, traffic lights and radios. They were found several years ago by Michael Harris, a self-described denim archaeologist, in an abandoned mineshaft in the American West. 

Like a Pollock canvas, the pants legs are speckled in wax from the candles miners employed to light the way. Advanced age is evident in the cloth patch along the beltline, a buckleback adjuster along the seat, suspender buttons and a single back pocket—details that only a pair from that era would have, Mr. Haupert said. He also relied on Mr. Stevenson’s expertise: “He’s seen everything under the sun. I trust him to confirm that they are an authentic pair from the 1880s.”

On the interior, the pants bear the phrase “The only kind made by white labor” printed on a pocket. According to a Levi’s spokesperson, the company used the slogan following 1882’s Chinese Exclusion Act, which barred Chinese laborers from entering the U.S. during a time of rampant anti-Chinese discrimination.

Levi’s subsequently adopted its own anti-Chinese labor policy, reflected in the “made by white labor” tagline on its products and in advertisements. In the 1890s, Levi’s scrapped its policy and dropped the slogan, the spokesman said. (The act was repealed in 1943 and condemned by Congress in 2011-2012.)