I've been eligible for 4 years but only got it last year, when we visited Cape Cod. Incredible bargain.
Ironically, we were in the water with our granddaughter for less than an hour when we were whistled out for sharks. Apparently this is a new thing there, with an increasing concentration of seals (bait).
call me a conspiracy theorist... but I think "seals" is code for "retirees"
If the park system plays their hand right, the sharks could help to alleviate future social security shortfalls by thinning the herd...
In other words, the Senior cards could be the lure that brings the retirees to the sharks... or bears... whatever creatures are willing to work with the government...
(disclaimer: yes, I'm kidding)