A lot of people seemed to think the census was this arbitrary thing, a department completely separate from all the others, & the census was designed to 'spy on' US citizens.
Actually, the Census Bureau is part of the US Dept. of Commerce, it's done to allocate how many seats a state gets in the US House of Representatives, & no, it isn't to spy on anyone.
But I recommend answering, because every response is one more body that gets counted when they figure out how much representation a state gets in Congress. Which is hellaciously important, in a representative democratic republic.