The U.S. Post Service expects today to be its busiest day of the year, thanks to the last minute rush of cards and packages being sent to arrive in time for Christmas. According to reports, "USPS says holiday mail will increase by more than 40 percent. That amounts to about 830 million pieces of mail in one day. Postal workers say you should send all your packages by December 16 if you want them to reach their destinations by Christmas."