“Interagency passes”
These passes allow free entrance to National Parks and some other sites. Check each site for applicability. Some passes confer different benefits; see below.
Some non-federal sites also honor the pass for day area fees, etc.
Price mentioned below were checked on Nov 2022.
The (America the Beautiful National Parks & Federal Recreational Lands Pass is the most common pass. It is annual and available to anyone who pays the $80 fee.
The senior pass is available to persons 62 years or older. It is available in annual ($20) and lifetime ($80) versions.
The free Access Pass for disabled folk is the most generous pass: because
At many sites the Access Pass provides the pass owner a discount on Expanded Amenity Fees (such as camping, swimming, boat launching, and guided tours).
Secessus says: “I've gotten discounts on stuff like water fills (50%) when the Access was the only pass allowed the discount.”
Vets and GS families can receive free lifetime passes.
Disabled vets may want to consider the Access pass instead. It's also free/lifetime, but
the [veterans] pass does not cover expanded amenity fees such as camping, tours or special recreation permits; reservation fees and fees for organized groups or concession-operated facilities or activities.