We’ve stayed at quite a few National Forest Service campgrounds as we’ve wandered the country. There are several things that make them appealing.
Of course, the biggest one, they tend to be in forests! We’ve taken advantage of them in Montana, New Mexico, Wyoming, South Dakota and now Arizona.
They’re rarely crowded. The campgrounds are usually remote enough that they aren’t often full, although, the closer you get to National Parks, the less that is true. They are well maintained and typically, are very clean.