DAR members throughout the world collect and donate books and other research material to both the national library and to the Illinois DAR Library. The NSDAR Library in Washington, D.C. is one of the nation's best genealogical research centers.  The Illinois DAR Library Collection is housed at the C.E. Brehm Library in Mount Vernon, Illinois.  Both libraries have searchable catalogues.  You can access the catalog for the NSDAR Library here.