Monday marks the busiest shipping day of the year

FILE - In this Feb. 7, 2013 file photo, packages wait to be sorted in a Post Office in Atlanta. The Postal Service on Friday reported a $5.1 billion loss for the just-completed 2015 fiscal cycle — but that's a slight improvement over last year. (AP Photo/David Goldman, File)

TAMPA, Fla. (WFLA) — If you are headed to the post office to put some last-minute Christmas gifts in the mail, you will have some company.

According to the United States Postal Service, Monday, December 19 will be the busiest mailing day of the year as 12 million customers visit the nation’s 31,000-plus post offices. About 750 million packages will be delivered this holiday season, which marks a 12% bump from last year.

If you want to make sure your gifts make it under the tree before Santa arrives, here are some important shipping dates to keep in mind:

SEND-BY DATES FOR EXPECTED DELIVERY BEFORE DECEMBER 25

USPS

December 20: First Class Mail

December 21: Priority Mail

December 23: Priority Mail Express

FED EX

December 23: FedEx First Overnight, FedEx Priority Overnight, Fed Ex 2Day (A $16 Saturday delivery fee will apply per package)

*FedEx Ground and FedEx Home Delivery will not deliver on December 24.

UPS

December 19: 3 Day Select

December 21: 2nd Day Air

December 23: Next Day Air