The National Register of Historic Places recognizes buildings, structures, objects, sites, and districts of national, state, or local historic significance across the United States. Out of over 90,000 National Register sites nationwide, more than 1,500 are in Washington.
^These counts are based on entries in the National Register Information Database as of April 24, 2008 and new weekly listings posted since then on the National Register of Historic Places web site. There are frequent additions to the listings and occasional delistings and the counts here are approximate and not official. New entries are added to the official Register on a weekly basis. Also, the counts in this table exclude boundary increase and decrease listings which only modify the area covered by an existing property or district, although carrying a separate National Register reference number.
^Several historic resources in Washington are included on multiple county lists:
Roberts, George; Roberts, Jan (1999). Discover Historic Washington State, Gem Guides Book Company, ISBN 1-889786-07-1.
Historic Places in Washington, Department of Archaeology and Historic Preservation, Olympia, Washington, 2008-10-01. The Washington Heritage Register includes all Washington sites on the National Register, plus numerous additional sites.