I'm not sure that the operation will receive the funding to be executed unless there is a legal necessity to change the Census. Yet explanations for the need to add the question are lacking. Doesn't the constitution demand that everyone is counted, not just citizens? Which kinda makes sense, because everyone is going to make use of utilities, roads, etc., not just citizens.
Cheers,
Bart
CORRECT POST
But not everyone can vote. Nor do illegals receive many benefits like Social Security. It's reasonable to know how many citizens are actually in each district who will vote and could receive these benefits. The census also finds out the ages of the people. This is information that is important for determining government actions in many areas. Census information is used by local government as well as business to plan development, zoning, government services, election districts, old-age homes, hospital needs, etc. If there are people there who aren't citizens, it would be nice to know the exact quantity, not just how many people of all kinds are there. Otherwise the result will be distorted and have substantial effect on government and private planning.
SCOTUS ruled that the question, in itself, is not unconstitutional. Unfortunately, the administration gave stupid reasons for including it that smacked of bias. So SCOTUS ruled that they couldn't include it. If Trump uses my previous paragraph and submits it to SCOTUS, it would probably be approved as a reasonable need.