You can get a Lifetime Senior Pass for $10. My wife and I have had one for 5 years and used it a lot..at Acadia, Glacier, Grand Canyon, Yellowstone, Yosemite, Arches, Bryce Canyon, Zion Canyon, Canyonlands, Mt Ranier, Ding Darling Bird Sanctuary, and we hope to use it this year at Badlands and Theodore Roosevelt
I've just learned the pass will be going up from $10 to $80 by the end of 2017. If you are 62+ this is a great deal if you do any traveling. Without it the fee to ride your bike/drive your car thru each National Park is $25.
You can purchase it online or at any National Park.
https://www.national-park.com/list-of-na...ed-states/