All that rain, sleet and snow can't stop them — but Christmas sure can give 'em a backache.

On Monday, more than a half-million pieces of mail went through the post office distribution center in North Charleston. If you didn't mail something, you may be the only one.

It is traditionally the busiest day of the year for sending packages and letters, with officials at the U.S. Postal Service estimating that about 1 billion pieces of mail nationwide went into the merry mix on Monday.

"We normally do up to 200,000 in a day," said Timothy D. Shaw, the postmaster.

You know what this means? You aren't the only one who has waited until the last minute.

"It's the way of the world," Ralph Posey said.

Posey stood in line Monday afternoon, packing packages as he waited in line. He's sending presents to family in North Carolina, and Posey is pretty sure they will get there in time — he's already checked. Besides, he knows the drill.

"I come in about twice this time of year," he said.

Having time in line gives you a chance to ponder philosophical issues, such as this: Although Christmas comes at the same time every year, somehow it always manages to sneak up on us.

"Very last-minute and I'm getting ready to go," Jennifer Nesbitt of North Charleston said, laughing. "I normally am a little quicker, but this year I'm just a little later."

The distribution center in North Charleston handles all the mail along the coast from Edisto to Georgetown, and from the ocean as far inland as I-95. It's one of four such plants, as the postal workers call them, in the state.

Shaw says the center brings in extra folks to handle the workload, which includes the line of people waiting in the lobby. While some people waited upwards of 20 or 30 minutes at some branches, the distribution center seemed to be moving a little faster.

"This post office is the quickest I've been to," Nesbitt noted.

The Postal Service says that if you want your First-Class mail and Priority packages delivered by Christmas, get 'em in by Thursday. The deadline for Express Mail by Christmas is Saturday.

In a related story, Wednesday will be the busiest delivery day of the year. So, odds are, you'll soon have mail.