Wednesday marked the birthday of a true American icon: the blue jean. It’s been 142 years since Levi’s received the patent for its riveted-for-strength denim jean. And for generations, the bottom has served as workwear, schoolwear, casual weekend wear, and been dressed up for date nights. But in its latest evolution, the very definition of denim is perhaps being compromised as makers are adding more and more stretch to jeans. And that’s being met with customer dismay, as they prefer the authentic durability of jeans like those Levi’s just added to its historical archives.

The athleisure trend has been blamed for a downturn in the denim business. But it’s only in recent years that so many denim makers have started substituting cotton for man-made materials—to the point where even premium brands have marketed bottoms as denim when they’re just 45 percent cotton.

Read more at Sourcing Journal.