Tuesday is expected to be a busy day with USPS officials anticipating 658 pieces of mail compared to 528 million pieces on an average day.
Consumers are urged to use complete mailing addresses on holiday mail -- including apartment numbers, directional indicators and zip codes.
Officials say Thursday is the last recommended day to send mail expected to arrive before Christmas Eve.
After that, USPS recommends the two-day Priority Mail service or overnight Express Mail.
The U.S. Postal Service expects to have delivered 17.9 billion cards, letters and packages between Thanksgiving and New Year's Eve.