The holiday shopping season traditionally begins with Black Friday -- the Friday following Thanksgiving. Shippers, meanwhile, have turned to new technologies to manage the load that comes as people have packages shipped from both brick-and-mortar and online retailers.

Mobile apps are one example. UPS introduced its free mobile app for smartphones this year. FedEx revamped its mobile web site and released an app for the BlackBerry. The Postal Service released an iPhone app back in January.

All three sets of apps provide various tracking capabilities and a way of finding the nearest location to ship from using the phones' GPS functions.

GPS, of course, was adopted years ago by shipping companies to track their vehicles and help plan routes. Radio Frequency ID tags have been used at FedEx for the last three years to help drivers open their doors without keys -- something that can be hard to do when juggling packages.

These kinds of technologies are all designed to make shipping more efficient, especially as the busiest days of the year approach.

The volumes give some idea why shipping companies are always seeking ways to make things easier.

UPS says its peak time comes at three days before the Christmas holiday, usually around Dec. 22, though that varies somewhat depending on what day of the week Dec. 25 falls on. On that day about 24 million packages are expected to go through the system.

Peak season begins on cyber Monday (the Monday following Thanksgiving), said Rebecca Treacy-Lenda, a UPS spokeswoman. The company expects to ship some 430 million packages between Cyber Monday and Christmas. Last year UPS shipped some 400 million packages, in the midst of a recession.

UPS is the main shipping provider for some of the largest e-tailing companies, such as Amazon and eBay.

FedEx, meanwhile, says its busiest day has fallen on the second or third Monday of December for the past five years straight, and that is unlikely to change. It was the second Monday in 2005. The company projects 16 million packages to be shipped this year, on Dec. 13. On Dec. 12, 2005, the peak day was 9.8 million.

FedEx spokesman Steve Barber says which days are busiest vary somewhat depending on what day of the week Christmas falls on.

This year, Christmas is on a Saturday. That will create two busiest days for the U.S. Postal Service, says spokesperson Sue Brennan. The USPS is still the busiest shipper, moving 560 million letters, cards and packages on an average day -- more than the yearly volume of UPS.

Dec. 20 will be slightly busier than Dec. 13, but only just, Brennan says. The USPS projects more than 15.8 billion pieces of mail between the day after Thanksgiving and Christmas Eve. And as the Postal Service is in a hiring freeze, they will have to do it with approximately the same number of employees. There will be a little extra hiring locally, but not much, she adds.