The U.S. National Park Service is celebrating 100 years of managing some of the nation's most well-known parks, monuments and historic places.

The agency's reach stretches coast to coast, from Acadia on the Atlantic to the Channel Islands in the Pacific. There's the Martin Luther King Jr. Memorial in Washington, D.C., and the Gettysburg National Military Park in Pennsylvania.

As the national parks system attracts greater numbers of visitors each year, the agency is facing key challenges ahead. One is a backlog of repairs that total nearly $12 billion. The other is reaching out to minority communities, who studies show don't go to the parks, and getting them to visit — and care about preserving — America's parks.

Centennial events scheduled for Aug. 25, 2016, include free mule-drawn boat rides at C&O Canal National Historical Park in Maryland, creation of a giant, living version of the park service emblem in Washington, D.C., a naturalization ceremony on the South Rim of the Grand Canyon and an outdoor concert at Yellowstone National Park.

National parks across the country are offering free admission, birthday cake, ranger talks and other special events to mark the anniversary.

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