The U.S. Postal Service says about 7,000 post offices will be open for extended hours during the holiday season.
It expects nearly a billion cards, letters and packages to be mailed December 17, the busiest day of the season.
That includes 275-million cards and letters.
The average daily volume for cards and letters is 82-million.
The postal service also encourages people to avoid lines by using automated postal centers, which are open 24 hours a day.