WASHINGTON — The sixth sentence of the Constitution, and the first one that specifically tells the government to do something, established the census.

It called for an “actual enumeration” every 10 years and, since the end of slavery, requires answers to just two questions: “How many people live in the United States?” and “Where do they live?”

The answers to those questions are the basis for American democracy, and much more. They determine, for instance, how congressional seats are allocated and where hundreds of billions of dollars of federal money are spent.

Next week, the Supreme Court will consider whether the Trump administration may add a question about citizenship to the 2020 “short form” questionnaire — the one that goes to every household in the nation. Nobody seriously disputes that this will cause fewer people to participate and will undermine the basic constitutional goal of counting everyone.