Lawrence’s annual sidewalk sale doesn’t officially begin until sunup Thursday, but workers at the Gap, 643 Mass., have been planning and preparing for weeks.

“It’s definitely our biggest sales day of the year,” said Annie Merrifield, store manager. “It’s about a month’s worth of traffic all in one day.”

Merrifield said about 40 employees would be on hand beginning at 7 p.m. Wednesday until late tonight or even into Friday morning.

She said because this sale was unique to Lawrence, the store — which is slated to start selling about 5 a.m. Thursday — received many shipments of discounted merchandise from Gap stores in the surrounding area.

“It’s a big process,” Merrifield said. “The amount of sale merchandise sent to the store is more than what we ever normally have on hand.”

But even with all of the work and the stress, Merrifield said the sidewalk sale was a fun day for her employees.

“Everyone gets a break to eat, and everyone gets a break to shop,” she said.

Shopping will take place from sunrise to sunset, said Jane Pennington, director of Downtown Lawrence Inc.

LJWorld.com will even help you find some of the best bargains. You too can help, and even win prizes. Just tweet with the hashtag #SWSale to be entered to win a prize.

For shoppers in need of a break, Billy Ebeling and the Late for Dinner Band will perform at noon outside U.S. Bank, 900 Mass., as part of the Brown Bag Concert Series.

“It’s a fun thing that we do all summer long, and it also just adds to the festivities of the sidewalk sale atmosphere,” Pennington said.

The Lawrence Transit System will also be offering free bus rides on the T from 6 a.m. until 8 p.m.

“Riding the bus means you can spend more time shopping and less time looking for a parking spot,” said Robert Nugent, Lawrence Transit administrator.

The sale typically draws 5,000 to 7,000 people each year and is one of the busiest days for local businesses.

“It’s a day of energy drinks and smiles,” Merrifield said. “It’s a Lawrence tradition, and we love to be a part of it.”