GPS locations were taken of every household and other types of living quarters last year in preparation of this year's census to make the maps as accurate as possible. Addresses and roads were canvassed at the same time to get the most accurate information available from interviews if possible, and from what was seen on the house or street if not. Sometimes neighbors were interviewed to get the most accurate location information. All locations were mapped that "could" have a person living in them this year April 1st.
This year is the real thing and you will either get one mailed, or more likely in rural areas, you will get one hand-delivered to you, or hung on your door in a bag if nobody is home. By law you must return it. Hopefully by April 1st. Filling it out before returning it is a good idea too. Addresses, roads and the previous GPS spots are also being checked and updated for as much accuracy as possible during this phase.
Next month there will be the group that goes around and follows up with the places that show no survey was received from, it was incomplete, duplicated, or for other factors. That is so that each is counted only once, and hopefully every place/person is actually counted that once.
Your Census information is covered by Title 13 of the United States Code. That covers your names, your address and GPS location, S. S. #'s and phone numbers. All census workers are sworn in and the penalties for giving out this information in your lifetime (76 years from now I believe it is, which would put me about 122 years old) is severe; up to 5 years in jail, $250,000, or both.
There are trillions of dollars that will be distributed using this census information over the next 10 years. The amount spent on the forms, the people, the Superbowl and other advertising are large amounts, but miniscule compared to the overall dollars these counts will impact for 10 years.
And no...it doesn't have anything to do with ACORN.
