They give you either a link where you complete the census online or a physical booklet with all the questions present to collect data from the population. What happens if you continue disregarding the census in the US? When was the last census conducted on the entire country? Even then, is answering questions on the census mandatory for both citizens and tourists alike? Also, what are the repercussions for providing false answers?
The census is mandatory, as others have noted. It is used for determining how many House seats each state gets, so it is important that it is accurate. And the Supreme Court has interpreted it to mean that an actual count has to be gathered everywhere, and that you can’t use statistical methods to derive the actual count.
So, even if they already have the information by some other means, they still need every household to give an affirmative response to the form. And if you ignore the form, they knock on your door to ask.
While they may have other questions they want you to answer, you are only obligated to tell them how many people live there, and their ages.(Edit: I looked it up, and I was wrong. They send a longer form to some households at random, and if you get that, you are technically obligated to answer all of those questions as well. )
Visitors don’t need to be counted, but anyone with legal permission to live here does, regardless of citizenship.
There is no punishment for not filling out the census so it isn’t mandatory to complete it. Census workers will do their best to count the people in the household based on what information they have if you don’t do the census, so it really is better to just fill it out to increase accuracy.
There is a punishment, on paper. You can be fined for not filling it out, or fined more for willfully lying on it. But, they have no enforcement arm, so it would be up to the Justice Dept to press charges, and I doubt they would bother.
https://money.com/what-if-i-dont-do-the-census