The president's comments come as the administration is trying to figure out a way to include the question.
ADVERTISEMENTWASHINGTON — President Donald Trump said Friday that the census needs to count citizens to determine how many seats a state gets in Congress.
"You need it for many reasons," Trump said. "Number one, you need it for Congress. You need for Congress, for districting. You need it for appropriations, where are the funds going? How many people are there? Are they citizens, are they not citizens? You need it for many reasons."
But apportionment of congressional seats has always been based on a state's total population, not just on the number of citizens.
The Constitutional Convention considered saying that a state's congressional seats would be based on the number of "free citizens and inhabitants" but rejected that in favor of the word "persons."
When Congress was debating the 14th Amendment, which provides further census guidance, it used the term "persons" instead of "citizens" or "voters."
In a 1964 case involving the one-man, one-vote principle, the Supreme Court said, "The debates at the Convention make at least one fact abundantly clear: that when the delegates agreed that the House should represent 'people,' they intended that in allocating congressmen, the number assigned to each state should be determined solely by the number of the state's inhabitants."
Over at least the past century, some efforts have been made in Congress to exclude non-citizens for apportionment purposes, but several of the sponsors have said it would probably require amending the Constitution.