From an AOTUS Blog Post by David Ferriero, Archivist of the United States:
The National Archives buildings were largely spared, thanks to extensive preparation based on “lessons learned” from similar weather events. I am grateful to all of our staff and especially to our facilities and emergency staff for their ongoing work in keeping personnel and records safe. None of our records were damaged as a result of Hurricane Sandy, thanks to our staffs’ careful preparation.
More about the pre-storm prep along with a couple of images in the complete blog post.