Dorothea Lange photograph of the Mochida family of Hayward, May 1942.
Soon after the attack on Pearl Harbor on December 7, 1941, public outrage and hysteria turned towards the Japanese (both alien and citizen) living in the United States. The west coast had a long history of anti-Asian agitation culminating in the denial of citizenship (naturalization) to Asians upheld by the U.S. Supreme Court in 1922 (Ozawa v. U.S.) and the 1924 Immigration Act which barred Asian immigration.
War with Japan quickly reawakened feelings of suspicion and fear. Newspaper headlines and columnists began to warn of saboteurs and fifth column activity. A report commissioned by Congress just after the Pearl Harbor attack largely dismissed these rumors and contended that the vast majority of Japanese Americans were loyal but it did nothing to stop the mounting public hysteria and government and military reactionism.
On February 19, 1942 President Roosevelt signed Executive Order 9066 which authorized the military to exclude any person from designated military areas. This order gave the military free rein to designate military areas and to remove any persons considered a danger. On March 2, 1942, Lt. General John L. DeWitt, West Coast commander U.S. Army, issued Public Proclamation No. 1 which designated the entire West coast a restricted military area. The Army issued the first Civilian Exclusion Order for the Japanese on Bainbridge Island on March 24, 1942. Though theoretically Executive Order 9066 could be used to remove German and Italian Americans only the Japanese community was forced to undergo mass evacuation and imprisonment.
By June 1942 more than 110,000 Japanese (more than 70% of them American citizens) had been forced from their homes into temporary assembly centers built at racetracks and fairgrounds. From the assembly centers the Japanese were moved to ten concentration camps scattered in the more inhospitable desert regions of the West where many would spend the remainder of the war.
For more background information on the incarceration of Japanese Americans see:
Map of Camps
Click on the map to see a larger version.