Some of the parks are offering rare and unusual events too. Science and the natural environment go hand in hand. In Yellowstone National Park, for example, scientists are monitoring gray wolves that have been reintroduced from Canada in the past five years. They're learning about the delicate balance between predator and prey and even between animals competing for the same resources. It's expected that the addition of the wolves will have a ripple affect across the park, changing populations of coyotes, elk and rodents.
Researchers even expect to find changes in the park's plant life as declining elk graze less.
The U.S. National Park Service also preserves sites where great scientific discoveries and inventions were made. They had overcome many obstacles in engineering and in understanding the fundamentals of aerodynamics. In 1916, the National Park Service, a federal bureau, was created to manage areas then assigned to the U.S. Department of the Interior. Long before there was even a park service, Yellowstone and other sites were set aside as national parks. Today, the National Park System covers over 80 million acres of land.