At the airport post office, people waited in line to send packages large and small.
"I was anticipating a longer line. That was one of the reasons I came to this post office because the line usually moves very quickly," said Esther May, who was mailing holiday packages.
Bruce McDonald said he usually doesn't wait until the last minute, but his newborn baby put him behind schedule this year.
"I don't expect they're going to get there in time, and neither do the people we're mailing them to," he said.
Several locations will be open later to accommodate for last-minute shippers. Some post office locations were even open on Sunday.
"We know customers are expecting their packages, so we do everything we can to try to deliver," said post office manager Sam Booth Jr. in Westchester.
Monday will be a busy day not only for the U.S. Postal Service, but for UPS as well. UPS said it will deliver about 22 million packages this season, and hired 50,000 seasonal workers to keep pace. Workers will sort and deliver roughly 400 million packages worldwide during the holiday season, which is up slightly from last year.
FedEx said its busiest day ever was last Monday. The company shipped 14.1 million packages, which is almost double the number on a typical day.
Economists are watching the volume of retail goods that are being shipped this season to track just how much consumers are buying.