The central stacks in the Humanities and Social Sciences section of the the 42nd Street New York City Public Library are closed while the library works on a project related to the façade restoration. 65% of the General Research Material is not available, including the Milstein Division of U.S. History, Local History & Genealogy.
You can read more about this on the NYPL web site at http://www.nypl.org/research/chss.
