US Archivist David S. Ferriero, announced on March 11, 2013 that the extended hours of 5 pm to 9 pm three days a week for Research rooms at the National Archives Building in Washington, DC, and the National Archives at College Park, Maryland, will cease effective Friday March 15, 2013.  The usual operating hours for the research rooms will continue Monday-Saturday 9:00 am to 5:00 pm.   The National Archives is also eliminating the extended hours for the exhibit halls when the building stayed open to 7:00pm through Labor Day.. The existing hours will remain from 10:00 am to 5:30 pm seven days a week.  The announcement did not mention any changes in the regional offices hours of operation.

http://www.archives.gov/press/press-releases/2013/nr13-73.html