The former hulking husk of a vacant Walmart here in the Rio Grande Valley is enjoying an unlikely second act. When the big-box retailer moved to a larger location down the street, the building might have been destined to house yet another large chain or to fall into disrepair. But rather than let the building become an eyesore, the city scooped it up and spent $24 million transforming the drab structure into a 123,000-square-foot public library that now serves as a vibrant space for the city’s residents.

The library, which is the largest one-story library in the country, has a modern, cheery feel. The twenty-foot ceilings combined with new skylights and windows give it a bright and airy interior. Large, three-dimensional signs that mark the sections hang from the ceilings, creating cozy nooks below.

The building includes a computer lab, a café, meeting rooms with videoconferencing capabilities and a 180-seat auditorium, among other amenities. This new space is a major upgrade from the old 40,000-square foot library, which had cramped shelves and limited seating.

“In the old place, basically every table or chair next to an electrical outlet was taken, and you had others glancing longingly at those seats. Now, we have outlets at all tables,” said John Donohue, the library’s circulation supervisor who has been with the library system for 31 years.

Administrators here embrace technology and anticipate a time when printed books are not the main focal point. “Libraries over the past two decades have been changing—the old stereotype was of a hushed, dark building and a librarian with a bun and sweater set hushing everyone,” said Kate P. Horan, the library director. “They have evolved to be more of a community space.”

The makeover wowed judges from the American Library Association and the International Interior Design Association, who named the McAllen library the overall winner of their 2012 Library Interior Design Awards.

Nods to nature were incorporated throughout the design—from some tabletops made from locally sourced mesquite wood to shades of green carpet in varying hues to mimic the patchwork of fields and citrus groves that one sees on a flyover of the Valley. Outside, a new façade, fountain, and a mix of native palms, live oak, and cypress trees disguise the building’s past life as a big-box store.

“You can make a beautiful building, but if it’s not used, its not a success,” said Bob Simpson, an architect from Boultinghouse Simpson Gates, the McAllen-based architecture firm hired to lead the project. “The library so far has exceeded expectations.”

That firm tapped Meyer, Scherer & Rockcastle, a Minneapolis firm with three decades of experience designing public libraries, to conceptualize the library’s interior. Together they were able to stretch the dollars in the city’s “responsible and modest budget” by reusing the old structure instead of starting from scratch, according to Jack Poling, MS&R’s lead interior architect on the project. (Other MS&R projects in Texas include a $3.3 million renovation that turned a former Food Lion into the North Branch of the Denton Public Library and the incorporation of part of a former YMCA into the plans for the Lochwood Branch of the Dallas Public Library.)

Big-box stores are being abandoned at a rapid clip, as retailers expand into larger spaces or go out of business. More than 130 former Walmarts are available for sale or lease around the country, and adaptive reuse of these spaces is only going to become more common in coming years, according to Julia Christensen, an assistant professor in Oberlin’s studio art department who has been studying this issue since 2002 and wrote the book “Big Box Reuse.”

“There’s not a landfill on earth big enough to put all the empty big box buildings in. They’re here. They’re either going to be used for something or they’re not,” Christensen said.

Local governments and school districts in the Rio Grande Valley have repurposed at least five big box buildings, including the Weslaco City Hall, which moved into a former Albertson’s grocery store in 2005. Coincidentally, across the street from the library sits a shuttered Kmart, which closed a few weeks after a March hailstorm.

Residents have flocked to the new library, which opened its doors in December. It is now serving more than double the number of patrons as the old building—some 62,000 people visited in July, up from 28,000 in July 2011.

Not everyone was an immediate fan of the location, however. Some frowned upon the idea of moving the main library outside the downtown district, which had been home to the main library since the 1920s. But consultants determined that the new location is close to the new geographic center of the city, which is shifting toward the northwest, according to Mike Perez, the city manager.

On a recent afternoon 72-year-old Alfredo Tobias Nogueira sat at one of the long white tables in the nonfiction section with a small netbook and several books spread out around him. The Cuban-born retired engineer spends four hours a day at the library, reading and browsing through the stacks for books on science.

“I’m a library bum,” Nogueira said. “I’ve been in libraries all of my life, and this is the best one I’ve ever seen. I’m talking about the building — the collection still has a long way to go, but for being a city library it’s pretty good.”