As museum problems go, crowding is a double-edged sword. It's proof of the obvious appeal of the place, but it can also discourage visitors from going there more often, or not returning at all.

That's why, officials said, a planned $28 million expansion of the Minnesota Children's Museum in St. Paul is so important — and why they're pleased that their $14 million bonding request won recommendation from Gov. Mark Dayton and landed in the House bill as well.

"Crowding is our biggest issue," said Dianne Krizan, the museum's president. "That's the great news, that we have an audience that wants to be here."

The museum, which drew 432,000 visitors in 2012 and is on a pace to pass that this year, wants to expand gallery and program space by 50 percent and redesign existing exhibits. The museum now occupies 65,000 total square feet.

Plans are to build out all four floors on the north side of the museum to W. 7th Street, fashioning an addition with a lot of glass to capture more natural light and showcase for passersby the fun going on inside the museum, she said.

The project will include a physical adventure gallery with a four-story climbing structure, an entire floor for imaginative and creative play, and an area devoted to STEM activities — science, technology, engineering and math.

Shuffling some of the first-floor offices also will open up some green space for play on the corner of W. 7th and St. Peter streets, Krizan said.

The museum expansion was on St. Paul's bonding wish list last year. But it ran behind the Lowertown ballpark, which won funding of $25 million.

This year it was the city's top bonding priority, said Joe Campbell, a spokesman for Mayor Chris Coleman. The museum is one of St. Paul's arts and culture organizations that generate about $330 million annually, including their budgets and money spent by visitors on lodging and food, he said.

The museum has about 15,000 member households, but it's no longer just a regional attraction. In the last two years the Minnesota Children's Museum has won national attention in Parents and Forbes magazines, both of which included it on their lists of best children's museums in the country. Many of the other museums on the lists were much bigger.

It ranks sixth or seventh in the U.S. among children's museums in terms of visitors, Krizan said. And it's a finalist this year for the National Medal for Museum and Library Services, a federal prize for innovation that will be awarded in a few weeks.

"The Children's Museum is a huge kids and family destination for St. Paul and draws people from every corner of the state," Campbell said. "It's part of the identity of the city and we're really proud of that."

The museum was opened in 1981 by a group of moms in the Minneapolis warehouse district as "Minnesota's AwareHouse," a place enabling kids to explore and discover with abandon. Almost immediately it proved too popular for its quarters, and four years later it moved to Bandana Square in St. Paul's Energy Park district.

It wasn't too long before museum officials again were confronted with the need to grow. After a lively site competition that included Minneapolis, they settled on downtown St. Paul. The redbrick and glass museum, costing $16.1 million, opened in 1995.

It hasn't been renovated since then, Krizan said. The major physical change was the addition of a rooftop art park and garden about 10 years ago, which also is slated for expansion.

Three years ago when the museum board was looking for a president who could lead their capital campaign and spearhead the museum's expansion plans, it decided Krizan fit the bill and hired her. Last fall the museum enlisted Minneapolis-based Meyer Scherer & Rockcastle as design architect for the expansion, a firm that has done several popular museums, such as the Mill City Museum in downtown Minneapolis.

The Children's Museum has been active on other fronts. A year ago this month it launched in Rochester the first of what it hopes will be a number of satellite locations. The small museum, in a strip mall not far from downtown, has drawn more than 35,000 visitors. It was started with the help of a $1 million grant from the state's Legacy fund, Krizan said.

The museum also recently formed a partnership with the University of Minnesota's Institute of Child Development, providing the institute with opportunities to apply research.

If the Children's Museum wins $14 million in state bonding, its goal is to raise an equal amount privately. So far $4 million has been raised, with some potential donors waiting to see what happens at the State Capitol, Krizan said.

If all goes as planned, construction would begin in the spring of 2015 and the expanded museum would open its doors in November 2016. It would stay open during construction for all but three or four months in late 2016, she said.

"It's an opportunity to re-invent ourselves and redo the museum," she said.