Washington – residents, 62 years, Oct – Mar, all parks, $50 pass

Off-Season Senior Citizen Pass - $50.00 gives you free nightly camping or moorage from Oct. 1 to March 31, and Sunday through Thursday in April. There is a $6 per-night fee for utility sites.
Offered to Washington state residents 62 years and older.
http://www.parks.wa.gov/passes/

Idaho – anyone, 62 years, 5 days of the week, 9 parks, no pass needed

Those 62 or older will receive 50% off camping fees within select Idaho State Parks.
The discount is valid mid-week on stays Monday – Thursday (excluding holidays), {anytime of the year}
North Idaho: Dworshak, Heyburn, Winchester
South Idaho: Lake Cascade, Three Island Crossing, Bruneau Dunes
East Idaho: Bear Lake, Lake Walcott, Massacre Rocks

Oregon – anyone, any age, Oct – April, all parks, no pass needed

Discount season for everyone at all Oregon Parks Oct 1 through April 30

discovered by Henry and Judy Lahore, Oct 2009