Chances are you've been to a park or historic area in the National Park System at one time or another. If it was in 2007, then your visit was one of an impressive 275,581,547 total recreation visits made to System sites last year alone.

To put that in perspective, consider that according to the Census Bureau the population of the United States is 303,763,031. Statistics aside, if you've ever tried to make a last-minute lodging reservation during the summer, you're already well aware of the popularity of the National Parks.

On August 25, 1916, President Woodrow Wilson signed the act that established the National Park Service as an office of the Department of the Interior.

The government’s aim, as stated in the National Park Service Organic Act of 1916, was to "conserve the scenery and the natural and historic objects and the wild life therein and to provide for the enjoyment for the same in such manner and by such means as will leave them unimpaired for the enjoyment of future generations."