Amidst fears of espionage and conspiracy, the Smith Act, or Alien Registration Act of 1940, enacted on June 28. The Act was a discriminatory pre-cursor to the numerous internment policies that would soon follow with the bombing of Pearl Harbor, especially towards Japanese Americans. Publicized as a national security measure, the Act mandated the registration and fingerprinting of all non-citizens, or aliens, in and entering the United States older than 14-years-old. In addition, the Act monitored movement such that non-citizens had to report changes to address within five days before facing criminal charges. In the subsequent months, nearly five million registered at post offices around the country. Although the alien registration forms have been destroyed, the Act stands out as a representation of distrust that would be critical in fuming the wartime hysteria that followed.
Source: U.S. Citizenship and Immigration Services