Postal carriers, who have been loaded down with holiday mail for weeks, are hauling extra stacks of advertisements and catalogs sent by businesses trying to beat the postage rate hike.

On New Year's Day at 12:01 a.m. local time, the cost of mailing a first-class letter will rise to 32 cents. Other postal rates will go up as well.The new rates have meant brisk bulk mailings and increased activity this week at post offices nationwide.

Mildred Slagle, a retiree in Frederick, stopped in the downtown post office Thursday to exchange her roll of 29-cent stamps for a roll of 32-cent stamps.

"It was a $3 difference. It's not really a big deal, but I think to businesses it is," Slagle said. "Remembering back to the 5- and 3-cent stamps - it's quite a change."

Margaret Brown, who bought her first 32-cent stamps and a supply of 3-cent ones to use with her leftover 29-cent stamps, agreed.

"If it keeps going up, it might be cheaper to call," she said.

The Postal Service has been selling temporary 32-cent stamps since Dec. 13. The stamp bears the letter G, an American flag and the words "Old Glory" but carries no price. Stamps with the new postal rates will be released this spring.

When the new rates were announced earlier this month, the U.S. Postal Service governing board said the increase - the first in four years - would reap an additional $4.7 billion in 1995 for the Postal Service, which lost $914 million in its last fiscal year.

The surge of mail sent by businesses and individuals trying to save a few cents per parcel started several weeks ago, said Greg Frey, a spokesman for the U.S. Postal Service in Washington, D.C. Most of the extra volume is third-class mail, such as advertising, some parcels and catalogs, he said.

Extra trucks and temporary workers the Postal Service hired for the holidays were kept on to help handle the anticipated volume, he said.