There’s a joke among locals in Nashville about how you can spot the tourists: They’re the ones in new cowboy boots, even in the hot and humid summer season. “Every girl walking around seems like they got boots on,” said Brent Taylor of New Orleans, exploring the Lower Broadway tourist district with his daughter, Morgan. “So I was like, ‘You want some boots?’”Sprinkled among the dozens of honky-tonks hosting live music at all hours of the day are boot shops.“It was worth looking. I found a few pairs that I like, and he got them,” Morgan Taylor said of her flat-toe footwear, green with silver sparkles. “I’ve been breaking them in. At first, they were painful.”She put them on immediately and joined the high-heeled stampede. In truth, it’s not just out-of-towners. Cayla Kessinger is a local who was taking in some live music while rocking calf-skin knee-highs with intricate stitching. They’re not her first boots, but they represent her commitment to the look.Cayla Kessinger poses in her “Old Gringo” brand boots, outside one of the many boot stores sprinkled among the honky-tonks in downtown Nashville’s tourist district. She calls them her first pair of “investment boots.” Blake Farmer/WPLN News“This is my first pair of investment boots, if you will, my first pair of legit cowboy boots,” Kessinger said. “Worth the investment. Worth the money. Could run a marathon in these things.”Not most people’s first choice for 26 miles, though the “Old Gringo” brand she’s strutting in can run more than $1,000. With boots, you’re often paying for comfort. The global market for Western boots has topped $1 billion by some estimates and is growing by nearly 5% per year. Publicly-traded retailer Boot Barn has surpassed 500 stores and has more than quadrupled in the last five years, now above $5 billion. So what’s going on? Some call it “the ‘Yellowstone’ effect.”Taylor Sheridan’s cowboy drama became a streaming sensation, now producing spinoffs that have people dressing as they do on the Dutton Ranch. The confluence of Beyoncé’s Cowboy Carter album also brought country music and style into the mainstream pop world. Lately, traditional country music has been reaching a wider audience. “Here in New York City, where I am right now, there is a humongous billboard right at Times Square with Ella Langley, sitting on a haybale, looking real chic, in her cowboy boots,” fashion writer Holly George-Warren said on an episode of WPLN’s “This Is Nashville.”Ella Langley’s hit song “Choosin’ Texas” broke Taylor Swift’s record for a female country artist’s run atop the mainstream charts. The pop crossover brings attention to her style too, though George-Warren, who wrote “How the West Was Worn,” said love for the cowboy boot has built over many years.“Both the music and the look have become global, and it’s been kind of a gradual process,” she said.The roots of the cowboy boot can be traced to Mexican cowboys, vaqueros. Country music artist Angie K, who was born in El Salvador, has been a daily boot wearer since she was young and said the fashion statement is strong everywhere she performs in the Americas. From New Mexico to Brazil, she plays for crowds in “a sea of cowboy boots and hats.”“And not just Hispanic people,” she said. “Every type of person, all in cowboy boots, all in hats, all in buckles.”And Angie K can’t recall the last time she played a show not in her boots. For both performers and fans, the boot is primarily fashion, not function. But the cowboy boot has become the functional equivalent of the country music uniform, said Lisa Sorrell. She’s a bespoke boot maker in Guthrie, Oklahoma, who is also writing a history of the cowboy boot. “I honestly wonder what would have happened if cowboy boots hadn't become stage wear and remained visible and in the public eye for so long,” Sorrel said. “I wonder if they would have gone back to being just a part of a cowboy's functional gear.”In Sorrell’s alternate history, you’d still have boots walking around ranches, but not so much on stage and screen — and almost certainly not on a honky-tonk bar crawl.