The U.S. Postal Service expects Monday, December 17, to be the busiest mailing day of 2012.

Postal workers will handle about 658 million pounds of letters, cards, and packages today. That's about 130 million pounds more than the average day.

The Postal Service says to expect lines but coming prepared could save you some time in line. Clearly print the address on letters and packages. If you do not know the recipient's full address, no ZIP code is better than the wrong ZIP.

Gift-givers still have until Saturday, Dec. 22, to ship express mail, and get presents under the tree in time for Christmas.