Last week, the Department of Commerce, which oversees the Census Bureau, announced that the 2020 census will ask respondents whether they are citizens of the United States. In response to what should be an unremarkable item of news, some on the Left have — of course — forecast a parade of horribles. They warned that Donald Trump was “sabotaging” the survey in a sinister ploy to consolidate power and strike fear in the hearts of immigrants.

But one purpose of any national census is to obtain basic and reliable data about the nation, and how many citizens reside in a country is as basic as it gets. That is why several countries, from Australia to the United Kingdom, include the citizenship question in their surveys. It is also why the United States includes the question in its own. Before 1960, the decennial census asked respondents if they were citizens. Afterwards, the question was included on the long-form questionnaire (issued as a supplement to the decennial survey to one in six households). In 2010, the American Community Survey replaced the long-form questionnaire, and it, too, asks the citizenship question.

Some have attacked the decision on quasi-constitutional grounds. The census is principally for determining the apportionment of House representatives, and federal law requires the census to count citizens and non-citizens alike for that purpose. But it does not follow that the census must preserve public ignorance about the number of citizens. The two are not mutually exclusive, and this decision does not change the way representatives are apportioned.