In 1916, Mackall was tasked, by
Wymberley Wormsloe De Renne, to fill in the spaces on the shelves of
De Renne Georgia Library, established by De Renne on the family's
Wormsloe Estate in
Savannah, Georgia. In 1920, he was elected to the
Century Association, having been nominated by Robert Grier Monroe and
Gari Melchers, Mackall's brother-in-law. Mackall was president of the
Bibliographical Society of America in 1936-1937. In 1937 he was president of the
Georgia Historical Society. He was also a member of Savannah's
Oglethorpe Club. == Death ==