The U.S. Postal Service is gearing up for its busiest time of year.

The post office expects to deliver 750-million packages during the holidays, up 12-percent from 2015. It will hire 35-thousand seasonal employees and will expand seven-day delivery to keep up with the load.

December 19th is expected to be the busiest mailing day of the year and December 22nd the biggest delivery day.

For U.S. delivery, officials suggest mailing ground packages by December 15th, First Class mail by December 20th, Priority Mail by December 21st and Express Mail by December 23rd.