Americas National Parks at 100 The National Park Service has been active for over a century preserving and protecting over 400 units across America, from the wild and natural to the man-made and historic. Take a tour through iconic Yellowstone and the Grand Canyon and discover smaller, hidden treasures throughout the country as we explore the agency's evolution over the last century. Through rarely seen footage and stunning aerial views, we celebrate the sites and stories of the national landmarks that reflect our country's past, present, and future.