The largest library in the United States (and also in the world) is the Library of Congress, with 32,332,832 volumes as of May 2009. Second is Harvard University with 15,965,675.
Boston Public Library is third with 15,760,879, followed by Yale University (12,283,594) and the University of California at Berkeley (10,725,334).
The largest library in Kansas (47th largest in the nation) is at the University of Kansas (4,210,639 volumes).
For a listing of the 100 largest libraries in the United States, see the American Library Association’s The Nation’s Largest Libraries.