The lines were long and the parking spaces were sparse at local post offices Monday as consumers dropped off gift packages and holiday cards for pre-Christmas delivery.

Caitlin Johnson showed up to the post office in Mount Pleasant on Monday afternoon to send Christmas gifts to Rochester, N.Y., where she's spending the holidays. Since she can't take all the gifts on her flight Dec. 22, she decided to mail them ahead of time.

"I didn't realize it would be this busy," she said. "I guess this will be my whole lunch break."

The Monday that falls a week before the holiday is typically the busiest mailing day of the year in the United States. Mail services expect to handle more mail this week than in previous years because of a hike in online shopping during the holidays.

In a pre-holiday report, Wells Fargo predicted that the average consumer would shop for 39.5 percent of his or her holiday gifts online, compared with 38.8 percent last year.

And a survey released this week by the National Retail Federation found that about half of consumers who hadn't finished gift shopping plan to do so online.

Global delivery company UPS predicted that it would pick up nearly 35 million packages Monday and deliver about 29 million on Tuesday, both record numbers for the company, a release said.

The U.S. Postal Service expected to process more than 600 million pieces of mail and to see nearly 6 million customers at post offices nationwide on Monday. The federal agency expects holiday mail volume to increase by 12 percent this year, according to a release.

Tanya Alexander, a supervisor of customer service at the post office on East Bay Street, said the lines on Monday were "brutal."

"It's busy all week, but Mondays are always the worst this time of year because people shop over the weekend and then come to send their gifts first thing Monday," she said.

Campbell McCraw waited in line at the Mount Pleasant post office with a wrapped present in hand on Monday. Over the weekend, she finished putting together a Christmas stocking to send to her boyfriend, who recently moved from Charleston to Jackson, Wyo.

"It's his first Christmas away from home," McCraw said.

Most customers at the post offices Monday were sending packages with expedited delivery so that gifts arrive by Christmas.

The office downtown sends out about three containers of express-delivery mail on an average day, Alexander said. By 2 p.m. Monday, it had sent out nearly three times that amount.

"Everybody has been waiting until the last minute," she said.

While the postal service typically sees the most customers on Monday, the heaviest days for delivery will be Tuesday through Saturday.

Reach Abigail Darlington at 937-5906 and follow her on Twitter @A_Big_Gail