Since the start of Taylor Swift's The Eras Tour, her fans have caused the ground to shake like an earthquake and helped boost hotel revenues. Now, they're helping a different part of the economy: bracelet material sales.

Thousands of Swifties have been buying the materials to make friendship bracelets — including colorful beads, letters, string, and charms — to trade with other fans that attend Swift's concerts.

The bracelets can consist of anything from a Swift song lyric to an album name to an inside joke among the fanbase. Originally, fans began making the bracelets to trade at the concerts because of a lyric in Swift's song "You're On Your Own, Kid" from the Midnights album.

"So make the friendship bracelets, take the moment and taste it / You've got no reason to be afraid" is the line fans are drawing inspiration from. However, this one line has led to a big increase in bracelet making material sales for some crafting stores.

More:Fans welcome Taylor Swift to Los Angeles: See the friendship bracelets, glittery outfits

Michaels art supplies and craft stores see 40% jewelry sale increase

John Gehre, the chief merchandising officer of Michaels Stores, wrote in an email to USA TODAY that the Swifties are a "large and loyal bunch" that have impacted the sales of jewelry for the company.

"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," Gehre wrote.

The increase in sales varies from place to place. Gehre wrote that in cities where Swift has tour stops, Michaels has seen a 300% sales lift in beads and jewelry categories in the days leading up to the concert.

"The largest jewelry category sales increase was more than 500% in Taylor’s home state of Pennsylvania, where she made two concert stops in Pittsburgh and Philadelphia, and the largest single-stop sales lift was more than 400% in Detroit," he wrote.

Michaels continuing to monitor inventory throughout trend

Gehre wrote the company has been following the bracelet-making trend since it began in April and adjusting inventory to make sure all Swifties are satisfied.

"As soon as we noticed the trend, our teams acted quickly to ensure inventory was available and well-merchandised in the stores to make it as easy as possible for customers to get in on the trend," he wrote.

While Michaels experienced a large increase in demand for craft supplies during the beginning of the COVID-19 pandemic, Gehre wrote that this is the first instance in recent years where "demand has spiked so acutely around a specific pop culture event and product category."

"While we may not have anticipated that lyric would spark such a huge trend, we were quick to identify it, anticipate what our customers would need from us, and ensured our stores were well stocked with the best supplies for Swifties to get creative and join in," he wrote.

Additionally, Michaels stores around the country have started building their own bracelet-making displays and offering bracelet-making in-store classes following the beginning of the trend. Over 22,000 bracelets have been made in the classes.

Fans should get supplies early, Michaels chief merchandising officer says

As fans gear up for the end of Swift's first U.S. leg of her tour on Aug. 8 and 9, Gehre recommends they get their bracelet materials as soon as possible.

"Shop early for your supplies, as these categories are selling through quickly in stores and online, but most importantly: enjoy the process of being creative," he wrote.

Looking forward, Gehre wrote that Michaels will continue to provide fans with the materials they need for the next U.S. leg of Swift's tour in 2024.

"We’re excited to see that Taylor is already planning to tour again in 2024 and we’ll be ready with everything our Swiftie customers need to partake in the fun," he wrote.

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Kate Perez covers trends and breaking news for USA TODAY. You can reach her via email at [email protected] or on X at @katecperez_