It has been all over the map in my experience this season.....
The trend I am seeing is if a campground is near a popular destination, the prices are high and they were sold out 6 months ago.
We stay at a campground near Raystown Lake in PA in each year. They raised the price 25% from last year to this year with no changes to the CG. They also raised their "visitor fee" from $5 (which I thought was ridiculous last year) to $8 this year. We spend the days on our friends boat and then they come over to our place for dinner. It cost me $48 to have them over 3 nights for two hours each night. We won't go back next year. Already booked a spot at the Raystown Lake Campground for 2022.
I booked all but one campground in January for our trip from August - October to Nashville, Teddy Roosevelt NP, Glacier, Yellowstone, Tetons, Mount Rushmore and Badlands NP because we knew this would be a very crowded camping year.
We just stayed at Boots Campground in Medora near Teddy Roosevelt NP and Fireside Buffalo Valley near the Tetons in the past few weeks. They were both $79/night for full hook-ups. Decent places but very basic and over-priced because of proximity to National Parks.
We just got to the Glenwood Springs KOA in Silt, CO last night. I booked it two days ago after we altered the rest of our trip. It may be the nicest KOA on our trip so far and it is $68/night for their premium patio site on the Colorado River. Their WiFi is good and the water pressure is 80PSI. We are a little over an hour from Vail so the price is very reasonable. This is a fairly large place and for a Sunday night in late September they only had 3 open spots left.
The other day I got lucky and got the last spot at the KOA in Green River, UT for Wednesday to Friday this week so we are going to hit Arches NP for a day on our way to Tucson to have the lousy Scwintek Slide System replaced with the Vroom Slide System.
Here are some pics for the $68/night premium sites at the KOA in Silt, CO.