George, if you will look at http://www.nps.gov/history/history/online_books/rthg/fore.htm
you might conclude it was Jesse Jackson Jr. and the year was 2000. Now, if you can find a way to get back to the year 2000 board posts, you may find it?
This pins it down a little more closely to May 2000
Google "National Park Service" "Jesse Jackson" and "Slavery" and you will get a bunch of hits
Hope this helps you find the entry point into Jim's archives.