By BRETT ZONGKER

Associated Press

WASHINGTON (AP) — After nearly 100 years, the National Park Service holds some of the most beautiful and historic places in the country, though there’s also an $11 billion backlog of unfunded maintenance and a visitor base that’s aging and mostly white.

With its centennial approaching in 2016, the park service has launched a major campaign to raise support and introduce a new, more diverse generation of millennials and children to “America’s best idea,” the national parks. First lady Michelle Obama and former first lady Laura Bush co-chair the campaign, calling on Americans to “Find Your Park” to enjoy their public lands.

Sustaining the national parks and keeping them relevant to visitors for another 50 or 100 years is a growing challenge, park officials told The Associated Press. Many facilities date back 50 years or more and are in danger of failing entirely, such as a 70-year-old water pipeline at the Grand Canyon that breaks regularly and could cut off the water supply to the popular tourist attraction, National Park Service Director Jonathan Jarvis said. Lodging at Glacier National Park needs a major overhaul, and the nearly 100-year-old Memorial Bridge in Washington, D.C., needs at least $150 million in repairs — more than the agency’s entire annual construction budget.

Behind the scenes, officials are seeking to expand fundraising through the National Park Foundation and bolster congressional support to improve the parks.

While the national parks counted 292 million visitors in 2014, those visitors tend to be older and whiter than the U.S. population overall.

“If we were a business and that was our clientele, then over the long term, we would probably be out of business,” Jarvis said.

The push to “Find Your Park” is the third major campaign in the national parks’ history.

An outcry over deplorable park conditions in 1915 originally led to the creation of the National Park Service. In the 1950s, there were calls to close parks because of their neglected conditions. That inspired a campaign to rebuild infrastructure and invite returning World War II veterans and their families to visit parks, with the memorable slogan “See the USA in your Chevrolet.”

“They came in droves, and in the back seat of that station wagon in the national parks were today’s boomer generation,” Jarvis said. “They are our base today … The question that we’re facing is who’s going to be the next generation of park supporters.”

In studying public perceptions, park officials found many people think national parks are only located in the West — places such as Yellowstone and Yosemite. They don’t realize urban sites such as the Statue of Liberty, Independence Hall in Philadelphia, Little Rock Central High School and the Lincoln Memorial in Washington are also national parks. So the agency wants to redefine the word “park” and show that these sites increasingly reflect the nation’s diversity.

Over the next year, an advertising campaign will include TV spots, digital ads and online videos about how people connect with their favorite parks. Corporate sponsors are supporting the effort with co-branded ads. American Express will encourage volunteerism in parks, while retailer REI and health insurance company Humana will promote healthy activity.

The White House announced an initiative to give all fourth grade students and their families free admission to the national parks during the next school year.

Celebrities including the science guy Bill Nye, actresses Bella Thorne and Roselyn Sanchez, E! News anchor Terrence J. and singer Mary Lambert are joining the effort, urging millennials to put down smart phones for some park time. Lambert, 25, said she has found inspiration for her music in parks, and she suspects more people her age are looking for places like parks to connect and have fun — beyond the Internet and social networking.

Nye said national parks are the legacy of the next generation to protect.

“The National Park Service is 100 years old. I hope you stop and think, ‘well why isn’t it 200 years old?’ ” Nye said. “It just shows you, I think, how close people came to sort of paving the whole country over.”