A number of new questions were asked including where people were five years before, highest educational grade achieved, and information about wages.

[2] As required by Title 13 of the U.S. Code, access to personally identifiable information from census records was restricted for 72 years.

Also, aggregate data for small areas, together with electronic boundary files, can be downloaded from the National Historical Geographic Information System.

During World War II, the Census Bureau responded to numerous information requests from US government agencies, including the US Army and the US Secret Service, to facilitate the internment of Japanese Americans.

In his report of the operation, U.S. Army Lt. Gen. John L. DeWitt wrote that "The most important single source of information prior to the evacuation was the 1940 Census of Population.