Post offices around the country are expected to be the busiest they've been all year.
One Postal Service worker says if you're mailing holiday packages and cards at post offices you should expect to wait.
"Be prepared to wait in line, have everything ready, have the customs forms filled out when appropriate ... and just to be patient," he said.
He says he likes helping customers around the holidays.
"It all depends on the customers' attitudes. If they're fine waiting in line and they're OK with it, then we're fine. We're OK it's actually kind of fun," he said.
Officials say the packages and cards must get in the mail by today in order to make it to their destinations by Christmas. That's if they're sent standard, first-class.