The citizenship question will be included on the decennial census for the first time since 1950, though it is asked on the annual American Community Survey. 

The decision to reinstate the question follows a request in December from the Department of Justice to the Census Bureau to add a question on citizenship.

According to a statement issued by the Department of Commerce, commerce secretary Wilbur Ross determined that “reinstatement of a citizenship question on the 2020 decennial census questionnaire is necessary to provide complete and accurate census block level data.”

Industry organisation the Insights Association has expressed concerns about the move to include a question on citizenship. Chief executive David Almy said: “Adding a citizenship question to the decennial census without appropriate testing introduces unknown accuracy risks due to the potential that it will deter legal or illegal immigrants from responding.

“Without testing and with fewer respondents, the decennial headcount likely will be less accurate, less valuable and unnecessarily expensive. To ensure accuracy, the census requires the highest possible representation of our population. Every subsequent survey and study that intends to be statistically representative of the US population will be built on decennial data, and any inaccuracies will be felt for at least a decade.”

The move could lead to a decline in response in immigrant communities, said Almy. “Marketing researchers know the expense of respondent cooperation better than most, as well as the potential downside of making any survey longer. Because of a lack of testing, the Census Bureau doesn’t know how much response will drop from legal or illegal immigrant communities, or other groups.”

The addition of the question could lead to an undercount in urban areas, adding to existing concerns over a potential undercount in rural areas: while Congress has boosted the funding for the census, this move likely came too late to help the Census Bureau replace already eliminated field tests in hard-to-count communities, the Insights Association said.

A number of states have signalled their intention to sue to block the addition of the question, the New York Times has reported. 

New York Attorney General Eric T. Schneiderman will lead a multi-state lawsuit on the issue, he said in a statement. Asking residents to share their citizenship status, he said, would “create an environment of fear and distrust in immigrant communities that would make impossible both an accurate census and the fair distribution of federal tax dollars.”