This week marks the centennial of the National Park Service: On August 25, 1916, President Woodrow Wilson signed the Organic Act, which established the National Park Service. The National Parks Service followed by many years the establishment of the first national parks: Yellowstone National Park was the first national park, established by Congress in 1872.

As we celebrate the centennial of the National Park Service, it’s worth remembering how important philanthropy was to the establishment of national parks and the National Park Service.

The establishment of the National Park Service owes much to industrialist and philanthropist, Stephen Mather. A keen conservationist, he advocated for an agency to tend to the country’s national parks. Mather ended up becoming the first director of the National Park Service. He not only headed up the National Park Service for a dozen years, he drew on his own fortune to buy land to expand national parks and to build visitor facilities and access roads.

Many of the national parks owe their origins to philanthropists. For example, philanthropist George Dorr donated much of the land that allowed for the 1919 establishment of Acadia National Park in Maine. Dorr persuaded others to donate their land to the park too. Among those he interested was John D. Rockefeller, Jr., who not only donated land but financed pathways that run through the park.

Philanthropists played key roles in developing parks not only in the early years of the National Park Service but in more recent years too. Oilman Wallace Pratt donated much of the land that, in 1972, became Guadalupe Mountains National Park in Texas. His home, “Ship-On-The-Desert,” which was built to resemble an oil tanker, is now park of the park.

Mary and Laurance Rockefeller donated their historic mansion and farm, as well as surrounding land, to establish the Marsh-Billings-Rockefeller National Park in Vermont in 1992; they then donated their JV Ranch to expand Grand Teton National Park in Wyoming in 2001.

Today philanthropists and conservationists continue to find new, innovative ways to protect our country’s land and natural heritage. Many of these involve free-market mechanisms. For example, nonprofits such as the Nature Conservancy and some individual philanthropists have simply bought up land for conservation. Some jurisdictions have created the opportunity for landowners to transfer rights to develop land, so that individuals may retain ownership while agreeing to leave their land undeveloped.

So, happy 100th birthday, National Park Service! And, as we celebrate, let’s celebrate the philanthropists who have done so much to protect our nation’s natural heritage.