This list may be helpful:Other Digital Sheet Music Collections
Source: Archive of Popular American Music, UCLA
> Lester Levy Collection of Sheet Music - Johns Hopkins University > African American Sheet Music - Brown University > Historic American Sheet Music - Duke University > 19th-century California Sheet Music - UC Berkeley > Music for the Nation - Library of Congress > Florida Sheet Music Collection - University of South Florida > Center for Popular Music - Middle Tennessee University > Charles H. Templeton Sheet Music Collection - Mississippi State University > Nineteenth-Century American Sheet Music Digitization Project - University of North Carolina at Chapel Hill > Keffer Collection of Sheet Music, ca. 1790-1895 - University of Pennsylvania > Performing Arts in America, 1875-1923 - New York Public Library > Sam DeVincent Collection of Illustrated American Sheet Music, ca. 1790-1980 - Smithsonian Institution