From my point of view, these letters are being sent according to areas so many will get their's later. Here's what I know. Every address in the US have/will receive a letter telling the recipient they will receive another letter that will be the actual census letter. These are sent first class, though of course the government doesn't have to pay what anyone else does for that service. Before I move on to the second letter, you need to know what the PO does with what we call "nixie" letters, those undeliverable letters. Nixies are sent back to the sender with one reason or another. However, this letter will not go back to the sender (government) and that is a savings of sort. Those letters are destroyed at the district (for me, Greensboro). Next comes the actual census form, again first class. Again, every address receives one of these. This letter however does not get the same treatment for nixies. The actually go back to the census bureau. There will also be a third letter, but I'm not sure what those will be, but all those nixies will be returned. Here's the thing that y'all should know about the census form. Those who have received it and filled it out will know that they ask that the barcode on the form show through the envelope. That barcode tells the census bureau exactly what address the form comes from. You guessed it, they compare the returns with the addresses that aren't nixies and those will be the addresses that an ACORN member will be knocking on the door for a head count. I have no idea what the census bureau will do with those forms returned with information that isn't what is expected. My guess is that some will also find an ACORN member knocking at their door, but I don't believe everyone will get that. I also don't know yet what happens to the third letters. Keep in mind that there are several reasons that first class mail can be returned. Refused and unclaimed are the two endorsements that will be used. So remember this, if you don't return your form, refuse it or in the case you have a PO box and it goes unclaimed, be on the lookout for an ACORN member before the year is out.