FedEx Corp. said today it expects to move 17 million shipments through its global system on Dec. 12, which the company predicts will be the busiest day in its 40-year history.

The Memphis-based transport giant said the pre-holiday surge represents a 10-percent year-over-year increase in projected holiday traffic. All told, FedEx expects to handle 260 million shipments between Thanksgiving and Christmas, a 12-percent gain over volumes that moved through its global network last year.

The company also said it would hire 20,000 seasonal employees to handle the surge. Last year, FedEx hired 17,000 seasonal workers.

The company said most of the gains would be driven by "FedEx SmartPost," a parcel-handling service managed in conjunction with the U.S. Postal Service (USPS) and largely aimed at e-commerce merchants like Amazon.com that ship packages to residences.

Under the service, FedEx moves shipments deep into the USPS system, where the Postal Service takes over to transport the merchandise the so-called "last mile" to the final destination. By law, the USPS must serve every U.S. residential address.

Rival UPS Inc., which would likely expect a similar pre-holiday package onslaught and which also uses the USPS network for residential deliveries from e-commerce sites, declined to comment on holiday traffic expectations or its plans to handle the surge. Atlanta-based UPS reports its third-quarter results early tomorrow.