Last week, the National Park Service reported that it had deferred $11.93 billion in maintenance for the fiscal year. This figure marks an increase of $440 million from the previous year. The news arrives just as the NPS is making plans for its 100th birthday.

The term "deferred maintenance" refers to work that needs to be done to keep NPS infrastructure, such as bridges, roads, campgrounds, trails or visitor centers.

Congress has allocated extra funding for the NPS in 2016, including an increase of $90 million for non-transportation maintenance. Congress also pledged $28 million more for transportation projects in the parks. Funding for transportation infrastructure maintenance will rise by $8 million per year for five years. In 2020, the section of the budget will be capped at $300 million.

One example of necessary maintenance is the Blue Ridge Parkway, which runs between Cherokee and Shenandoah National Parks in North Carolina and Virginia, respectively. Fifteen million people travelled the parkway in 2015, making it the NPS's most-visited site, even more popular than the Golden Gate National Recreation Area. The parkway's deferred maintenance totals $516.6 million.  

"While Congress provided increases this year, the annual bill for maintenance in America's national parks is still almost twice as much as is appropriated," said Jonathan Jarvis, director of the NPS, according to the report.

"Congress has pitched in with base funding," said Jarvis, "and with additional funds for the Centennial Challenge - a program that enables us to leverage private and non-profit partner contributions to complete important projects that improve visitor services in parks. There is more Congress can do through the Centennial Act now under consideration including short-term mandatory appropriations."

Paved roads appear to be the costliest item to be repaired. In Utah's Zion National Park, $69.85 million in deferred maintenance has accumulated. Of that, paved roads account for $54.07 million.