The Trump administration recently restored a citizenship question to the full decennial census, starting with the year 2020. When critics charged that the new question may reduce response rates, some confusion ensued as to when and how the Census Bureau has asked about citizenship in the past. The following table gives the history of both the citizenship and birthplace questions.

Questions Included on

Decennial Census, 1790-2020 Birthplace? Citizenship? 1790

1800

1810 No No 1820

1830 No Yes 1840 No No 1850

1860 Yes,

but free inhabitants only No 1870 Yes Yes,

but asked only of men 21 or older 1880 Yes No 1890

1900

1910

1920

1930

1940

1950 Yes Yes 1960 Yes,

but 25% sample only No 1970 Yes,

but 20% sample only Yes,

but 5% sample only 1980

1990 Yes,

but 1/6 sample only Yes,

but 1/6 sample only 2000 Yes,

but 1/6 sample only;

also asked in first annual ACS Yes,

but 1/6 sample only;

also asked in first annual ACS 2010 No,

but asked in annual ACS (~3% sample) No,

but asked in annual ACS (~3% sample) 2020 No,

but to be asked in annual ACS (~3% sample) Yes,

also to be asked in annual ACS (~3% sample) Sources from Census Bureau: "Measuring America", September 2002; "Index of Questions"; "Census Bureau Submits Planned Questions for 2020 Census to Congress", March 29, 2018. The annual American Community Survey (ACS) began in 2000. It covers approximately 3 percent of the U.S. population and is conducted separately from the decennial census. In 1960, birthplace and citizenship were asked of the entire population of New York and Puerto Rico. Because this is not a representative sample of the United States, the citizenship cell still gets an unqualified "No".

Traditionally, Census questionnaires have asked only for basic demographic information, since burdening everyone with a long set of questions would cost too much time and money. In the mid-twentieth century, the Census Bureau devised a way to obtain more detailed data in a cost-effective manner. It added supplemental questions — the "long form" — that would be answered by a representative subset of the population. After 1950, both the birthplace and the citizenship questions were removed from the full census and demoted to the long form. The birthplace question moved to the long form in 1960, while the citizenship question began appearing on the long form in 1970.

The long form ended with the 2000 Census. The American Community Survey (ACS), an approximately 3 percent sample conducted annually, now fulfills the long form's role of gathering detailed data, including birthplace and citizenship, from a subset of Americans.

With the ACS in place, the 2010 census returned to the short single-form style for the full population, with no citizenship question. The 2020 census will be similarly spartan, but the citizenship question has been added back. As the table indicates, the Census Bureau has regularly asked a representative subset of U.S. residents about citizenship, but this will be the first time since 1950 that the full population will be asked.

Will including the citizenship question lower response rates? Steven Camarota, director of research at CIS, is testifying before the House Judiciary Committee this morning on that issue. His testimony is available here.