It may not be that helpful in Alsaka, but if you want more information you can go to the National Park Service web-site
I have a Golden Access passport (for disabled). It is free, but I rarely use it as I feel I should pay the fees to maintain the parks, as long as I am able to do so. For a disabled person with limited income, it would be a blessing. I was told that inside the national parks, the Golden Access passport can also be displayed on the dashboard for a disability parking permit. I used it for that and didn't have a problem so guess it's true. The Golden Age passport is for persons aged 62 and older and is a lifetime admission and discount card. Check out the website for more information.