Should the 2020 census include a question about citizenship status? Of course.

The Constitution requires an “actual Enumeration” every 10 years, and it is essential that the enumeration be an accurate, fair count of the total population, including the number of citizens and noncitizens. Knowing that distinction is crucial, as we use census data to guide everything from the distribution of federal funding to enforcement of the Voting Rights Act.

A citizenship question was a standard — and non-controversial — part of the census until 2010. The previous (2000) survey employed two different census forms: one short, one long. The long form contained additional questions — including a citizenship question — to gather socioeconomic information. It went to one out of every six households.

The long form was discontinued after that 2010 census. The additional questions from that form were, instead, shifted over to the American Community Survey. The Census Bureau reports that, while it sends out the ACS “on a rotating basis through the decade,” only one in 38 households receives it.

In other words, the ACS goes to only a limited number of geographic areas and a much smaller share of the population than the long form it replaced. Still, the Census Bureau uses the data it collects to provide “estimates” of “demographic, social, economic and housing characteristics” for other geographic areas across the country. Why would we want to rely on estimates based on limited survey data when we can do an actual enumeration?

Citizenship information collected in the 2000 census was vital to our efforts to enforce the Voting Rights Act when I worked at the U.S. Department of Justice. When reviewing claims of whether the voting strength of minority voters was being diluted in redistricting, it was essential to know the size of the citizen voting age population.

Without knowing citizenship, for example, it is not possible to know what percentage of Hispanic voters are needed in a particular congressional district to elect their candidate of choice, which is the key test under Section 2 of the Voting Rights Act. As the Justice Department noted in its Dec. 12, 2017, letter to the Census Bureau asking that the citizenship question be reinstated, multiple federal courts have held the “citizen voting-age population is the proper metric” in such cases.

As a nation, we are currently engaged in a vigorous debate about immigration. Having an accurate count of the number of noncitizens is obviously essential to an informed debate. Without that data, it is impossible to discuss numerous issues intelligently — everything from how many immigrants we should accept every year, to whether chain migration should be maintained, extended, limited or ended.

Some claim that the question will deter people residing in the country illegally from responding to the census. But the citizenship question on the ACS, which is currently used, simply asks whether the person is “a citizen of the United States.” If you answer “no,” the form does not ask you whether you are in the country legally or illegally. The long form previously used by the Census Bureau, such as the 1990 census, used the same question. There was no follow-up question about lawful status.

When designing a survey that is intended to give as accurate a picture as possible of the American body politic, more information is always better. Not only should the Census Bureau reinstate the citizenship question, it should be on every census form sent to every resident of the nation in 2020.