Matthew B. Gilmore
Washingtoniana will close its doors at the Carnegie Library on July 7, 2017.
Preparations for construction of the (fast-tracked) Apple global flagship store, as described here: http://intowner.com/2017/06/14/plans-for-major-rehab-enhanced-use-of-historic-carnegie-library-building-now-moving-forward/ are due to begin.
Access to Washingtoniana collections is expected to resume in the fall (date not yet set or announced), somewhere at the Newseum.
Materials at the Peabody Room and the Library of Congress are unaffected.
Bear in mind these resources (and many others) available at the National Archives and Library of Congress: