Today is the busiest mailing day of the year.
This season alone the US Postal Services expect to process 9 billion cards, letters and packages.
Some Christmas mailing deadlines to keep in mind:
December 16: last day to ship "parcel post" - the cheapest shipping service.
December 20: last day to mail first-class and priority mail.
December 23: last day to ship express mail in order for the gift to arrive in time for Christmas