National Park Week is underway, and free entrance to nearly 400 parks continues through this Sunday.
In celebration of the festivities, the National Park Foundation, the non-profit behind the fee-free week, shared with HuffPost Travel some surprising statistics about what Ken Burns calls "America's Best Idea."
America's national parks, by the numbers:
- 84 million: The total acreage of the parks, an area roughly the size of Germany.
- 281 million: The average number of people that visit a park every year.
- 18,000: Miles of trails traverse the parks.
- 45,000: People who volunteer at America's national parks.
- 13.2 million: The acreage of the largest park, Wrangell-St. Elias in Alaska. (It covers an area larger than Costa Rica.)
- .02: The acreage of the smallest, Thaddeus Kosciuszko National Memorial in Pennsylvania. (He was a Polish soldier who joined the Continental Army during American Revolution.)
- 0: The number of national parks in Delaware, the only state without one.
What park gets the most visitors? The Blue Ridge Parkway, the 469-mile drive that threads the Appalachian Mountains of North Carolina and Virginia.