Your Skinny Jeans Are Destroying the U.S. Dollar—Literally

Spandex has "contaminated" the cotton that's been used to make our bank notes.

Shutterstock/Petrenko Andriy
If you happen to be looking for reasons to be angry with Kim Kardashian, here's one more: She's messing with your money. Or, well, her famous affinity for spandex is. Fashion's current obsession with tight-fitting clothes, The Washington Post's Ylan Q. Mui reports, is causing, among so many other things, problems for the U.S. currency.
The first thing to know here is that paper currency is not actually—technically—printed on paper, the stuff of trees and pulp. It's printed, rather, on a cotton blend that is specially formulated to withstand the various foldings/crumplings/occasional launderings that bank notes endure. As the Treasury's Bureau of Engraving and Printing explains it: "United States currency paper is composed of 75 percent cotton and 25 percent linen. This is what gives United States currency its distinct look and feel." 
Also aiding that distinct look? Since the 1800s, Mui notes, when the U.S. consolidated its money into a single system of currency, the fabric-like paper used for banknotes has been produced by a single company: Crane.
So Crane, to do its job for the government, needs cotton. And you know who also uses cotton? Clothes-makers. Crane, to create its bill-worthy blends, long turned to the garment industry. And to, in particular, denim manufacturers, which provided Crane with scraps of their denim—the oddly-shaped leftovers from jeans and jackets and the like—that the company could then repurpose into currency. In 2010, a Levi's executive described the scrap collection process as it played out in a Mexican fabric warehouse: 

At the cutting room, all of the denim scraps left over from cutting the fabric was collected and packed into bales. They look just like the white raw cotton bales the fabric comes from, although these were blue denim scrap bales.

Crane, apparently, once got about 30 percent of its cotton in this manner—making denim one of the company's largest single sources of fiber for U.S. bank notes. (The other 70 percent came from a mix of other textile remainders.) The company bleached and otherwise processed the denim scraps, converting 501s into fives and ones.
Which was all kind of wonderful, actually. Inter-industry cooperation! Recycling! Upcycling!
And it all worked quite well—until, that is, the 1990s. Since then, denim manufacturers have been adding spandex to their offerings, particularly to their pants, availing themselves of the clingy fabric's ability to tighten and stretch simultaneously. This has been, with the obvious exception of jeggings, a generally good development for the jeans-wearing public.
It has been a less-good development, however, for American currency. As Mui explains it,

Even a single fiber of spandex can ruin a batch of currency paper, degrading the strength of the material. But separating the spandex from the cotton would be a Herculean task, [Crane's managing director of global sourcing Jerry] Rudd said. By the early 2000s, almost every pair of jeans contained at least a hint of stretch—rendering them useless to Crane.

"There's no denim products out there that we can find that's basically not contaminated," Rudd put it.

Contaminated! While there is perhaps an ingenious way to work spandex into our bills—Benjamins are Benjamins, stretchy or no—Crane has been changing its cotton-sourcing strategy in response to the skinny-jean phenomenon. The company, Rudd told Mui, now looks "beyond the waste stream" to "the natural fiber itself." It now buys cotton, in other words, rather than repurposed denim. Which is a transformation you can blame on fickle fashion trends. Or on Americans' expanding waistlines. Or on, if you'd prefer, Kim Kardashian.