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 88,000 NRHP sites nationwide,Oregon is home to more than 1,950 NRHP listings.[a]
Over one-fourth of the NRHP listings in the state are found in Multnomah County. In turn, the large majority (over 90%) of Multnomah's NRHP sites are situated within the city of Portland.
^The Oregon state list dated June 6, 2011, gives subtotals by county and total of 1,927. The total in this list differs due to newer listings recorded here, and due to specific data discrepancies that have been identified.
^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 such increases and decreases carry a separate National Register reference number.
^Several historic resources within Multnomah County are included on multiple area lists: