I sent a copy of the post on sheet music on line to my daughter, who
replied with the list below.  The first two links (UCLA & Duke Univ.)
also link to further collections.

Del Lohuis

 - - -

Sheet Music consortium
  http://digital.library.ucla.edu/sheetmusic/ 

Duke University Library
  http://library.duke.edu/music/sheetmusic/collections.html 

Library of Congress - specifically
  http://memory.loc.gov/ammem/smhtml/smhome.html 
  http://lcweb2.loc.gov/diglib/ihas/html/volcano/volcano-home.html 
  http://lcweb2.loc.gov/diglib/ihas/html/civilwar/civilwar-home.html 
    (civil war sheet music)

Massachusetts Institute of Technology
  http://libraries.mit.edu/music/sheetmusic/index.html