Census workers are allowed to go door to door to peoples addresses who have not filled out the census survey.
However while the census worker is allowed to walk up to your door and knock and try to get you to answer the census they cannot make you answer the census.
You can refuse the census and the census worker must leave your property when asked to do so.
There's not much a cop would do if you called them on the census worker but if you threaten the census worker then they might call the cops on you.
Just politely ask the census worker to leave your property and to not come back.
Although it says you must take the census poll by law there's really not much they can do to force you to take the census other than give you a fine.
I refuse to take the census and nothing has happened in the 15 years of refusing the census and my father has refused to take the census before as well.
My father even once threatened a census worker with a gun and told him to get off the property and he did and never came back.
I don't recommend doing that though but that is just what he did.