The book Circular of General Information Regarding Yellowstone National Park, Wyoming says, "Camp sites occur 3 miles, 7 1/2 miles, 12 miles, and 13 miles from West Yellowstone." (link)
All that is left at the 3, 7.5, and 12-mile distances are road pullouts. The 13-mile campground matches the location of the current Madison Junction Campground.
If you have any more information about these campground locations, please let me know: bavetta@gmail.com