NARA, the U.S. National Archives and Record Administration,now called just Archives, has just begun to display its holdings, almost all of which cannot be found elsewhere. For starters look at the collection of WWII posters and often-cited but not in full documents like the Emancipation Proclamation and the Japanese Surrender at the end of WWII. Information about the relocation of many Japanese in the United States can also be found by visiting the Smithsonian site.
U.S. National Archives and Records Administration On-Line Exhibits
Resource Link: https://www.archives.gov/exhibits