The new Hennepin County branch library in Brooklyn Park is about as Instagrammable as any public building you'll ever see. From the Ojibwe canoe-inspired bike rack to the wall of glowing multicolored tubes for instant art and the wind tunnel spitting out toys in the kid zone, it radiates high spirits.

But there's a growing disconnect between the increasing razzmatazz of library buildings and the traditional vital signs of library performance.

In an era of extensive building and remodeling of library facilities, the Minnesota Department of Education is reporting drops in the number of visits, registered users and loans of material. The use of library computers is down sharply, as the number available to the public surges.

The $23.5 million Brooklyn Park library got an admiring mention last month from the national Library Journal. But the Journal gave no stars to the Hennepin County Library system, once an elite five-star performer, for the second straight year.

Librarians respond, in the words of the Hennepin system's Ali Turner, that "numbers don't tell the whole story." Of the system's lost stars, she said: "It is an honor [to get them] and we like to be part of that, but it's a bit of a numbers game" for a system that is "not solely focused on volume but on quality."

The reaction in St. Paul, where the library system also lost its national three-star rating in recent years, is similar. "It's hard to know what those numbers are telling us," said spokeswoman Phoebe Larson.

It may just point to a metamorphosis in the purpose of the facilities. Both state and national experts agree that there's a lot more to libraries these days than traditional measures such as visits and materials lent. The digital age is making it challenging to measure how useful libraries are, as people tap into databases from home rather than set foot in a building.

The star system "is not an index of the quality of your service, it judges you solely on things we can get data about," said Keith Curry Lance, a Denver-based consultant who coproduces it.

In the metro area, the Ramsey County Library system has gone in the opposite direction from Hennepin and St. Paul, achieving star status in recent years that it didn't have before. Much of suburban Ramsey County boasts upscale demographics, with 75 percent of households having a library card. Officials from other systems point to the Roseville branch as a star performer, leading the state in visits and circulation.

"Roseville is beautiful and huge," Larson said. Added Turner: "Roseville is right in that sweet spot of being perfect to drive to, and having the coffee shop. But circulation is not the only mark of excellence."

A focus on quality

In terms of national reputation, the Hennepin system isn't suffering, Lance said. "It has been legendary in the library world for as long as I've known the field," he said.

One major change for the system was its 2008 merger with the Minneapolis city libraries. The latter had to be rescued from "dire straits," said Hennepin County Commissioner Peter McLaughlin. "Libraries were closing. It was really in trouble."

Data compiled by state officials for the Star Tribune show that the combined Hennepin/Minneapolis system now is open for business fully 24,646 hours a year more than it used to be; all other metro libraries combined show just a tiny uptick. The 2006 deal to build Target Field included money for library hours.

The national data also show that Hennepin has invested in desktop computers for users to an extraordinary degree compared with other big systems. Did it overspend for that, when trends are moving to more use of patrons' own devices on library Wi-Fi? Turner says no.

"We still see intense use of desktops and a lot of waiting," she said. "We sometimes move machines to different branches according to demand."

The state's data show that the Hennepin system is the only big one in the metro area to register a drop in people attending programs at the libraries in the past 10 years. At the same time, a huge flow of state arts and culture funding has helped push other metro area systems' performance from 292,000 attendees a year to 458,000.

That's a classic case where numbers can deceive, Turner said. "We are not solely focused on volume but on quality," she said. "When we do a workshop for artists on business plans, or writing workshops, we may not draw 300 people … but we are perfectly comfortable with a high-impact strategic approach."

Amid some skepticism from analysts, there's a move away from quantity measures and toward attempts to document the quality of what libraries do. There's a lot of buzz about the national Public Library Association's "Project Outcome," described as an effort to "help public libraries understand and share the true impact of essential library services and programs."

Happy patrons

The new $23.5 million Brooklyn Park library is proof that the very mission of libraries is changing. Beyond the flashy experiences for kids, there's a recording studio in the teen area, more space for meetings, plug-ins everywhere for mobile devices and a conference room suitable for Skyping on a huge flat screen.

"I grew up with the old library here," said Alissa Knutsen, who brings 2-year-old Kilik once a week. "I couldn't believe the setup here. My son just begs and begs and begs to come to the library."

Kathryn Zimmerman, whose title at the library is "patron experience supervisor," said she was amazed when Hennepin County's Maple Grove branch opened a few years ago. But Brooklyn Park, she said, "is a whole 'nother level."

Knutsen said her 2-year-old was drawn to the library by the social fun but doesn't just play on the flashy toys; he brings home 15 books a week. Officials said the library lent out 10,000 more items in July than in the same month in 2015, with similar jumps in the months after that, and issued 490 new library cards in August vs. 192 in the same month the year before.

The new-style library is producing happy patrons, Lance said, but he's suspicious of efforts to document the value gained via the kinds of user surveys libraries are leaning toward.

McLaughlin's take: In an era when the concept of a library is evolving, challenges arise in documenting library quality. "But I don't see its value waning."

David Peterson • 651-925-5039