South Dakota

There are 32 CGs within 15 miles of Mt. Rushmore. Very popular area. Probably help if you could narrow it down to the type of CG you're looking for. On my last trip, I stayed at the Mt. Rushmore KOA, with FHUs including cable, WIFI, and a concrete patio with picnic table. But there are also dry camping CGs in that same area as well as anything in between.
Also be aware that Aug. 3rd thru the 9th is the 75th annual Sturgis Motorcycle Rally - just 50 miles away. Every CG will be crowded. I was there during the rally one year. No trouble, but LOTS of traffic.