First, it was a frenzy of people at malls and shopping centers looking for holiday gifts.
Now, millions of shoppers are looking for post-Christmas deals and returning presents they may not have wanted.
The National Retail Federations says the day after Christmas is one of the top five shopping days of the year.
The U.S Postal Service, FedEx and UPS are expected to be swamped with returns too.
UPS says it expects to handle two million packages headed back to stores during the first week of January.
The biggest day for returns by mail is January 3rd.