If you're planning to spend more than 5 days visiting national parks during a year time period, it makes sense to purchase a $50 National Park Pass. Entry into some of the more premier parks, such as Yellowstone and the Grand Canyon are $20 alone, so it doesn't take too much time to recoup your investment.

(Update - This card has been superceded by the America the Beautiful - National Parks and Federal Recreational Lands Pass which now costs $80. So do the math and figure out whether it makes sense. For us this past summer it was cheaper to pay for the individual parks.)

This pass provides admission into any National Parks, Monuments, Historical Sights, etc. and is valid for one full year from it first use.

For an additional $15, a Golden Eagle hologram may be purchased and affixed to a National Parks Pass to cover entrance fees at not only national parks, but also at sites managed by the U. S. Fish and Wildlife Service, the U. S. Forest Service, and the Bureau of Land Management.