What time does USPS deliver packages?
They start delivering to the several PO Boxes and to those who had the special overnight or 1-2 day stamp before noon. Then they get a hour off to sort through, change shifts if they had to and then pick back up with normal mail. Do know that if you ordered a package and paid the extra money to have it shipped to you and it arrived after 12 noon, you can take it to the closest USPS office and request a refund of the total difference.