On August 25, 1916, President Woodrow Wilson signed a law that created the National Park Service. It was designed to manage and care for the U.S. national parks. At that time, the United States had 35 national parks and monuments. Some of them had already existed for years, such as Yellowstone National Park. Established all the way back in 1872, Yellowstone was first national park in the world. Today the national park system includes more than 400 parks. It also includes monuments, battlefields, and other historic sites. These places cover more than 130,000 square miles (336,700 sq/km). Approximately 300 million people visit them each year. To celebrate its centennial, the National Park Service is planning special events it hopes will draw even more visitors to U.S. national parks.
Photo of Gibbon Falls by Yellowstone National Park/Flickr Creative Commons.