Colorado State Park annual pass

Also, all vehicles must have a pass. So there is a $35 charge for the towed vehicle if you pull such. It is good for the same time frame as the original pass. Still a good deal in my opinion and goes for a good cause. They can be purchased on line or at any state park in Colorado if staffed. They are also sold at some of the big box sporting goods stores .
http://www.parks.state.co.us/ParksPasses/Pages/ParksPassInfo.aspx