The 1940 census, officially the Sixteenth Decennial Census of the United States, was conducted with a reference date of April 1, 1940. It enumerated a national population of 132,164,569, an increase of 7.3 percent from the count a decade earlier. The work was carried out under the direction of the Census Bureau and produced data used for congressional apportionment, federal planning and historical research.
Scope and headline results
The count measured basic demographic characteristics such as age, sex, race, marital status, and place of residence. It also continued to track urban and rural distributions and regional population changes. The overall rise in population reflected continued recovery from the Great Depression and internal migration trends that shaped the nation before its entry into World War II.
New questions and methodology
The 1940 enumeration introduced several questions not previously asked in prior decades. Enumerators recorded where each person lived five years earlier, which made it possible to trace recent migration patterns. The census also asked about highest level of education completed and collected information about wages and income for workers. A portion of households received additional sample questions to gather more detailed social and economic data.
Uses and significance
Data from the 1940 census have been used to allocate seats in the House of Representatives and to guide public policy and infrastructure planning. For historians, demographers and genealogists, the records provide a snapshot of American life on the eve of World War II, illuminating employment, schooling, household composition and mobility during a pivotal era.
Access and historical notes
Under the federal 72-year privacy rule, individual-level 1940 census records were made publicly available in 2012 and have since been widely consulted by researchers. Original enumeration forms, summary reports and analytical publications issued after the census remain primary sources for studying population change between the 1930 count and later decades; the 1930 figures are commonly cited for comparison with 1940 results (1930 population).
For further institutional and reference material about the census itself see the official designation of the Sixteenth Census and contemporary agency descriptions archived by the Census Bureau and related repositories.