They don’t have any problem limiting visitors to Yellowstone in the winter so why don’t they limit the visitors in the summer?  Almost 3 million will visit during the busy 6 months of the park, it can't handle that much volume on its infrastructure.  People should be able to go online or call, get a pass for as many days as you would like, then go.

 

It would make for a better experience, ease the over-crowding, and not stress park resources.  Plus they would not have to collect money at the gate, you would just show your pass, and then you’re in.  The park and visitors to it would be better off.