MIAMI (CBS4) – If you finished your Christmas shopping over the weekend and planned to ship your gifts out Monday at Post Office, join the crowd.

The U.S. Post Office said Monday will be their busiest day of the year.

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For some who were waiting in line at a Post Office in Pembroke Pines, they were very familiar with the last minute rush to get everything shipped out.

“If my stuff arrived on time my family would pass out because they are not used to anything I send coming on time,” said Karen Nowack.

“I have to take care of this today otherwise, you know, I won’t, I’m not going to make it,” said Bella Perez.

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Postal officials expect 800 million pieces of mail to be handled on Monday, 40 percent more than the average daily volume.

“We will postmark approximately two or three hundred thousand more cards tonight at each processing center, we have one in Miami, one in Ft. Lauderdale and in West Palm Beach,” said USPS spokeswoman Debbie Fetterly. “Today is the reccomeneded deadline for First Class Mail, letters and packages.”

If you wait until Tuesday you will need to ship gifts using Priority Mail. Those who wait until the very last-minute (Wednesday) will need to use Express Mail to make sure their packages arrive before Christmas.

Priority Mail Flat Rate boxes are available for free at any Post Office.

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If you want to save time at the Post Office, you can go online at and buy postage and print labels and customs forms using Click-N-Ship. Information on free package pickup is available online.