Taylor Swift’s Eras Tour has inspired thousands of fans to make friendship bracelets to trade at concerts. The idea is based on a lyric in “You’re On Your Own, Kid” from Midnights: “So make the friendship bracelets, take the moment and taste it / You’ve got no reason to be afraid.” And the trend is having a noticeable effect on the economy.

“Overall, sales in our jewelry category, including jewelry-making kits, are up more than 40% chainwide since mid-April, when the friendship bracelet-making trend really began to take off,” John Gehre, the chief merchandising officer of Michaels Stores, told USA Today. But in cities where Swift has tour stops, that increase grows to 300% in the days leading up to the concert.

It’s not just Michaels either, people with Etsy shops are also benefitting.