Some of the Largest Libraries in the US are in Massachusetts.

The Largest Libraries in the U.S.

Rank  Institution  Volumes (as of `06) appear below:

 

1.  Library of Congress  29,550,914

2.  Harvard University  15,181,349

3.  Boston Public Library  14,933,349

4.  Yale University  11,114,308

5.  Chicago Public Library  10,745,608