Are illegals supposed to, by law, be counted in the Census?
Included in the total population counts to allocate House Districts among the States?
Used for drawing State Congressional District Boundaries?
IMO, only citizens should be counted. Not green card holders, H-1B’s or other legal aliens. It’s incomprehensible why citizens in areas swarming with non-citizens should get a bigger say in the House or the Electoral College.
The Constitution doesn't distinguish, so yes.
"Representatives shall be apportioned among the several States according to their respective numbers, counting the whole number of persons in each State, excluding Indians not taxed."
Yes. Here is the official government website for the U.S. Census
https://www.census.gov/programs-surveys/decennial-census/2020-census/about.html