President Donald Trump’s plan to add a citizenship question to the 2020 census has sparked controversy in Washington and beyond. Below, Princeton University scholar Douglas S. Massey answers questions about the census and how this might change the way information is collected.

Massey is the Henry G. Bryant Professor of Sociology and Public Affairs at the Woodrow Wilson School of Public and International Affairs. His research focuses on international migration, race and housing, discrimination, education, urban poverty and Latin America, especially Mexico.

Q. What is the history of the census?

Massey: Some may wonder why people are so worked up. After all, the census began asking about citizenship in the 19th century and it has been a part of every census enumeration since 1890. However, some background is required to put the issue into perspective.

After 1950 the census was divided into a “short form” that went to all households and a “long form” that went to a sample of around a fifth of the population. The short form only asked about the basics: age, sex, race, etc. Detailed data on individual social and economic characteristics — like education, occupation and income — were gathered using a much larger set of questions listed on the long form, which also included the question on citizenship. The goal was to reduce the burden of responding to the census by limiting detailed questions to a subset of the population.

In 2010, the long form was replaced by the American Community Survey (ACS), which was designed to be administered every year in order to provide reliable demographic data between decennial census dates. Data from the 2010 ACS essentially substituted for data that used to come from the long form, and, since 2010, the citizenship question has been asked on the annual ACS.

Q. President Trump plans to insert a new question to the 2020 census: “Is this person a citizen of the United States.” Why is he including this?

Massey: What President Trump is doing is moving the citizenship question from the ACS to the short form census that goes to every household in the United States. According to Secretary of Commerce Wilbur Ross, this action is being taken so that federal officials can combine citizenship data from the census with administrative data obtained from the Social Security Administration and the Bureau of Citizenship and Immigration Services (in the Department of Homeland Security) to develop block-level estimates of who is a citizen and who is not. Ostensibly, this shift is being made to improve enforcement of the Voting Rights Act, but in my view this rationale isn't credible given the administration's pullback on enforcing civil rights laws in virtually all other venues, including housing, employment and criminal justice, just to name a few.

Q. What are the ramifications of this? What is your overall reaction to its inclusion?

Massey: The attempt to locate concentrations of non-citizens on a block-by-block basis needs to be set in the context of an administration that was elected on an explicit white nationalist platform. Trump announced his candidacy by asserting that immigrants from Mexico were "rapists" and that the nation was “not sending its best people," a phrase later simply abbreviated as "bad hombres." During the campaign he called for prohibitions on the immigration of Muslims and upon assuming office sought to ban immigrants from several Muslim countries. He also expressed his view that neo-Nazi demonstrators in Charlottesville included "many good people" and more recently that we don’t need immigrants from "shit hole countries."

In this context, the plan to develop and make public which blocks throughout the United States contain high concentrations of non-citizens is chilling, especially given the experience of the 1940s when the Census Bureau provided block-level data to federal officials on the location of Japanese Americans in states throughout the West in order to facilitate their detention and internment. In an era of mass deportation when the arrest and detention of immigrants are at record levels, block-level data are much more likely to be used to target foreigners for persecution than to guarantee the voting rights of minority group members. This realization, of course, is not lost upon the nation’s Latinos, both immigrant and native, and will serve to reduce the likelihood of their successful enumeration in the 2020 census and thus under-represent the areas they inhabit for the legislative reapportionment that begins in 2021.

WWS Reacts is a series of interviews with Woodrow Wilson School experts addressing current events.