Gift exchanging extended for at least one day for families whose packages didn't make it under the tree on time.
Jason Lee said he was doing some last-minute online shopping with Amazon, but still was expecting his order by Christmas Eve.
"For the kids, most of their stuff did arrive, so they're happy. But I did have one gift for my mother that was the big wow gift for her that didn't arrive. I was sad about that but hopefully it comes today and I'll get it to her today," said Lee.
UPS hasn't said exactly how many customers were impacted.
Laura Lechtzin thought she might be one of them after doing a lot of online shopping this year.
"They were able to deliver everything on time. We didn't have any late packages...They actually were good about letting us know if things were going to be running behind and we did receive tracking notices via email so it was really good," said Lechtzin.
In a statement, UPS apologized to everyone who experienced delays.
A representative explained, "the volume of air packages in our system exceeded the capacity of our network as demand was much greater than the forecast."
FedEx also admitted to late deliveries but called them "isolated incidents" releasing a statement that read, in part, "Our 300,000 team members delivered outstanding service during this holiday season, and we experienced no major service disruptions in the week before Christmas despite heavy volume. Every single package is important to us, and we will continue to work directly with customers to address any isolated incidents. Customers with questions about their shipments should contact FedEx Customer Service at fedex.com or (800) GO-FEDEX."