Happy 100th Birthday, National Parks! Sorry You're Falling Apart.

The parks enter their second century with a $12 billion backlog of repairs.

WASHINGTON ― Thursday marks the 100th anniversary of the National Park System, which has been described as “America’s best idea.”

Today the National Park Service oversees 409 sites, 23 national trails and 60 “wild and scenic” rivers. These parks are among the country’s most prized assets ― enjoying high public regard and record attendance last year, with 307 million visitors.

Repairs and upgrades to paved roads, bridges, and parking lots make up nearly half of that backlog. Another half involves the parks’ facilities, including dams, utility systems and amphitheaters.

Funding for the National Park Service has fluctuated slightly in recent years, but hasn’t kept pace with needs. With an eye to the centennial, the Obama administration asked Congress for $860 million for the service in its 2017 budget, which lawmakers have yet to appropriate.

Meanwhile, the maintenance backlog is having real effects. Here’s an example from Grand Canyon National Park, which is among the most popular. The Trans-Canyon Pipeline, a 16-mile pipe built in the late 1960s that brings water into the park, needs replacing. It’s been in use 20 years longer than it was supposed to be, and it breaks down five to 30 times a year, the park service says. While parts of the pipeline have been replaced, it would cost $150 million to do the entire job ― which is pretty much impossible for a park with a $20 million annual budget.

Another example: Most of the roads in Yellowstone National Park, another much-visited site, have not been upgraded since the 1930s and ‘40s. Repair costs are estimated between $850 million and $1.2 billion.

Other deferred maintenance costs are listed here by state and park. And it’s not just deteriorating infrastructure; the parks are also having problems with the day-to-day stuff. NPR had a segment earlier this year about how staff cuts at Great Smoky Mountains National Park have workers struggling to keep its toilets clean and its trashcans from overflowing (the story includes this unforgettable line, “If you’ve got to lube a trash can, it might as well be in paradise, right?”).

Nasty bathrooms, crumbing trails, pothole-laced roads ― all of those are becoming problems at parks across the country, said Emily Douce, the associate director of budget and appropriations at the nonprofit National Parks Conservation Association.

“It really impacts the visitor experiences,” said Douce. “The park service, to their credit, does try to put the band-aids on those issues as much as they can. But underneath, the infrastructure is falling apart.”

Interior Secretary Sally Jewell, who oversees the park service, noted the backlog in a speech on the centennial earlier this year. She warned that budget crunches “have left our national parks and public lands understaffed and struggling to keep up with day-to-day operations.”