Denim has a long history, meaning that “vintage” denim can be anything from a pair of shredded, late 19th century overalls unearthed from an abandoned mining site to your mom’s stonewashed duds from high school.

Right now vintage Levi’s from the ’80s and ’90s are having a major fashion moment. Women are showing up in them on street style blogs, Re/Done is reconfiguring them with new fits and Urban Outfitters is rewashing huge batches and selling them under their Urban Renewal line.

Denim consultant and trend analyst Amy Leverton explained that the current heritage trend is a reaction to the financial crisis. “When people are economically unstable, they are drawn towards things that are built to last and remind us of a simpler time.” She added, “Nowadays the mass market brands aren’t built to last so people gravitate towards symbols of longevity.” However, she also said that heritage as a trend is now on its way out.

Henry Wong, director of product development and marketing at Artistic Fabric & Garment Industries, explained that there are a few factors that all came together to make vintage Levi’s such a runaway success. They first became trendy after brands like Current/Elliott started creating boyfriend jeans as an antidote to the super skinny jean; the initial designs for these boyfriend jeans were based on vintage Levi’s, mainly from the 80s. Around this time, stylists started buying vintage jeans for people like Rihanna, and then they started showing up in street photography and on Instagram. On top of all that, Levi’s from the ‘80s and ‘90s are easily accessible because they were made so recently and consumers can still buy the jeans at thrift stores for $5.

On the other hand, ’80s and ’90s Levi’s have no value to a purist denimhead, Wong pointed out—though denimheads do love older Levi’s. Leverton explained that part of the inherent value of the brand is that there are so many garments that you can trace the history pretty closely, generating a lot of collector’s value. Antonio DiBattista, Blue Blanket founder, said that Levi’s overalls are the most coveted item, and Leverton added that more wearable items like early jeans and railroad jackets are also hits with collectors. She added that perennial favorites are Levi’s Type I or II jackets and a Levi’s XX jean.

Outside of Levi’s, vintage denim collectors also covet the other very earliest denim brands, which are now defunct. Along with Levi’s, there were several workwear brands that looked to serve the market of prospectors going West in the late 19th-century. One of these is Boss of the Road, which was an initial competitor with Levi Strauss that went out of business around WWII. There is also Can’t Bust ‘Em, a San Francisco-based workwear brand that was later bought by Lee in the 1940s.

The issue with the more obscure denim brands is that there simply isn’t enough supply to meet the demand. Wong explained that there is a hunger for obscure denim specifically in the Japanese market. In response, there are a few brands reproducing rare vintage workwear. One of these brands, the Japanese brand Warehouse, works specifically with the obscure brands in America’s history, such as Boss of the Road and Copper King.

Leverton commented on the nostalgia related to these brands, “This goes back to the very reason denim is still so important: these brands stand for quality, craftsmanship, longevity, and they also symbolize the backbone of America: good honest hard work.”