In 1942 Carl Zigrosser began a collection of artists' letters, papers, signatures and photographs here at the Philadelphia Museum of Art. He called this the Archives of American Art. In the 1950s the Smithsonian Institution organized a national collection of microfilmed American artists' papers and also called it the Archives of American Art. In 1954 the Smithsonian microfilmed much of Zigrosser's collection to add to their microfilms. Zigrosser acquired the Leila Mechlin and Henry Schnakenberg collections. Later, Kneeland McNulty also added material to the PMA Collection. Previously maintained in the Print Department, the CZC collection is now in the Archives, indexed and arranged alphabetically by artist.