You still have time to ship a package and have it arrive ahead of Christmas. However, it will likely cost you more than it would have if you shipped it last week.
USPS
(Last day to ship for expected delivery before Dec. 25)
Priority Mail Service - Dec. 19
Priority Mail Express Service - Dec. 23
FedEx
(Last day to ship for expected delivery before Dec. 25)
FedEx Express - Options from Dec. 20 to Dec. 23
UPS
(Last day to ship for expected delivery before Dec. 25)
UPS 3 Day Select - Dec. 20
UPS 2nd Day Air - Dec. 21
UPS Next Day Air - Dec. 22
