GREENSBORO, N.C. – With just days to go before Christmas, many are thrown into a cooking, cleaning and prepping frenzy. And, the post office is also in the middle of a frenzy as well.

The U.S. Postal Service says December is always their busiest month, but this year, there has been more mail sent and delivered than ever before. It's estimated between Thanksgiving and New Year's Day, postal workers will deliver fifteen billion pieces of mail, nationwide.

It's still an all-hands-on-deck operation behind the doors of the Greensboro distribution center, especially in the middle of the night, as workers make sure packages are delivered by Christmas.

What starts with just dropping of a Christmas card or package in a sometimes-slow-moving line at the post office, ends up at the distribution center, which is the opposite of slow-moving – as every piece of mail is sorted by machine and by hand.

Edward McLean Jr. has been working for the United States Postal Service for 40 years. Now a manager, he makes sure this machine runs smoothly. He says things have certainly changed.

“In the last 40 years, I would say, it's the technology – of the machines, the equipment and the ability of the Postal Service to process more mail in a shorter period of time,” he said.

That's especially true during the busy holiday season.

“Right now packages are up about 10 percent, over what they were same period last year,” said Greensboro Postmaster Ronnie White.

“We had our heaviest day on Monday,” said Jason Dechambeau, the Senior Manager for the distribution center, “And we processed outgoing, mail that's originating here in Greensboro for packages alone, about 125,000 pieces.”

But McLean and his team have it handled.

“The last two or three days at the plant, things start tapering off on the outgoing side. But on the destination side - the volume is still there. We're still trying to get those packages home,” he said.

The mail carriers are still working long hours, and they will be until Sunday morning.

If you haven't sent your gifts yet, you have a little time. Friday, December 22 is the last day to ship with USPS, but you'll have to use Priority Express.

Friday is also the last day to ship using UPS, for your packages to be delivered before Christmas, but you must ship using UPS Next Day Air. Keep in mind, packages will be delivered on Saturday, but Saturday Delivery is not available in all ZIP codes.

FedEx has a few options as well, but it is getting down the wire if you need your presents to arrive before Monday, December 25.