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.Center for Immigration Studies