During World War II, the Stockton Assembly Center was built on the San Joaquin County Fairgrounds, a few blocks from what was then the city center. One of 15 temporary detention sites run by the Wartime Civilian Control Administration, the center held some 4,200 Japanese-Americans removed from their West Coast homes under Executive Order 9066, while they waited for transfer to more permanent and isolated camps in the interior of the country. The center opened on May 10, 1942, and operated until October 17, when the majority of its population was sent to Rohwer, Arkansas. The former incarceration site was named a California Historical Landmark in 1980, and in 1984 a marker was erected at the entrance to the fairgrounds.