Photos show how FDR's 'tree army' helped shape America's national parks — and how the NPS has changed since

Members of the Civilian Conservation Corps (CCC) at a camp in Oregon.

CORBIS/Corbis via Getty Images The National Park Service, created by President Woodrow Wilson, turned 110 years old on August 25.

Its 12,600 full-time employees oversee 85 million acres and manage a multibillion-dollar budget.

Recent cuts have threatened the agency's ability to maintain its operations and visitor levels.

Before federal rangers became stewards of America's 63 national parks , responsibility was fragmented among several agencies — including the Department of the Interior, the US Army, and the Forest Service.

At the time, federal lands, largely in the western US, received minimal management due to a lack of coordinated leadership and policy from the era's politicians.

Some Americans also questioned the idea of converting land and monuments into parks.

That all changed on August 25, 1916, when President Woodrow Wilson signed the " Organic Act of 1916, " creating what is now known as the National Park Service.

In the first decade following the act's adoption, American industrialist and conservationist Stephen Tyng Mather became the first NPS director and helped establish Grand Canyon, Acadia, Bryce Canyon, Zion, and Denali (formerly Mount McKinley) as national parks, and successfully lobbied for legislation allowing the purchase of land from private owners in the eastern US.

Today, the NPS — which celebrated its 110th birthday on Tuesday — oversees 433 sites across 85 million acres of federal land , from national parks and monuments to historic sites, battlefields, trails, rivers, and recreation areas.

The goal is to conserve each location's scenery, wildlife, and historical objects.

The NPS has also worked alongside numerous federal work-relief programs over the decades, particularly during the New Deal era .

The Civilian Conservation Corps, or CCC — Franklin D' Roosevelt's so-called "tree army" — was one of them.

Within months of the program's creation in 1933, the US Army and other agencies were developing plans to have 250,000 young men in camps around the country by July 1 that year.