There are three National Forest Service campgrounds near the southern end of Spearfish Canyon [1]. None of them require reservations. Contact the Black Hills National Forest office at 605/642-4156 for more information. All are primitive sites with no electricity. There are restrooms and running water. Maximum length of stay at any of the campgrounds is 14 nights. Two of the campgrounds are located south of Savoy, off of Route 222.
The Rod and Gun Campground (Apr.–Dec., $15) offers seven sites just three miles down Route 222 on the left. Located beside Little Spearfish Creek, this is a high-elevation campground sitting at about 5,500 feet above sea level. It is very close to where the winter scenes in Dances with Wolves were filmed.
The Timon Campground (Apr.–Dec., $15) is another 1.5 miles past the Rod and Gun Campground. It also has seven sites right beside Little Spearfish Creek and is at an elevation of more than 5,600 feet.
The Hanna Campground (closed in winter, $15) is located off of U.S. 14A about 3.5 miles south of Savoy (about 0.5 mile north of Cheyenne Crossing). The campground has 13 sites and is located next to Spearfish Creek. In the summer, there’s an on-site host.
Links:
[1] http://www.moon.com/destinations/mt-rushmore-the-black-hills/the-northern-hills/spearfish/spearfish-canyon-scenic-byway