Camping, which began in 1951 in Oregon's state parks, has never been free*. A fee to park during the day at some state parks started in 1981. Then, and now, you can enter any state park on foot or by bike for free -- the fee is to park.
 
We have about 300 properties in the state park system; 26 charge a parking fee. We are not funded by taxes. Revenue from people who directly use parks makes up more than a third of the money needed to staff, clean, and protect each park in the system.
 Yes but...camping was much cheaper with much less emphasis of keeping cars out.
 
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* There is one state park campground, Succor Creek, where it's not practical to charge a fee, so it's free.