There is also RI stuff in the Copeland collection at Northwestern U. IIRC 1956 was the last year. Erie too.
When Earl Tuson was at Northwestern, he photocopied the Index Northwestern had of the Copeland Material. Earl then added them to the STMFC's Files titled "Copeland." The files appear to be more extensive than those at the Baker Library at Harvard. Another repository for Copeland data is the Barringer Collection at the old St. Louis Mercantile Association now located at the University of Missouri - St. Louis. I have heard of no one accessing Barringer's Copeland Files.