Downtown merchants were busy Monday marking down prices on a variety of items. They were preparing for Thursday’s 32nd annual downtown sidewalk sale.

The sidewalk sale, which runs from sunup to sundown, is expected to attract about 20,000 people to the downtown area, organizers said. Downtown Lawrence Inc. director Maria Martin said most retailers would open at 7 a.m. and close at 8 p.m.

Marked-down prices seem to draw most shoppers, retailers say, but some also are attracted to the atmosphere.

“It will be a bit of chaos down here Thursday, but people like this because it is an event,” said Dan Hughes, co-owner of Sunflower Outdoor & Bike Shop, 802 Mass. “It is like coming to the carnival.”

Martin, who also owns downtown’s Southwest and More, 727 Mass., said shoppers thrived on the hectic atmosphere.

“The hustle and bustle excites shoppers,” Martin said. “We don’t mind crowds. I kind of like shopping last-minute at Christmas time because everybody else is out and it creates an atmosphere. The sidewalk sale is kind of the same thing.”

The downturn in the national economy isn’t expected to put a damper on the annual sale. Retailers said they had noticed shoppers being extra cautious with their money, but they doubted it would cause people to skip the event.

“I would argue that you might even see more people hunting for stuff at cut-rate prices because of the economy,” Hughes said.

Hughes said items would be marked down from 20 percent to 60 percent.

Alix Greenwell, manager at Sunflower Outdoor & Bike Shop, 802 Mass., labels sale items for the annual sidewalk sale in downtown Lawrence. Thursday's sale is expected to draw about 20,000 people to the downtown area.

The sidewalk sale provides a boost for virtually every downtown retailer, Martin said. For some it ranks among their best sales days of the year. Hughes said it was Sunflower’s largest single sales day.

“We’ve been preparing for what to put out for sale for months now,” he said.

Hughes even brings in a former employee who now lives in Colorado. The employee sits on top of a lifeguard-style stand barking out rhymes about merchandise the store has for sale.

“It kind of adds to the atmosphere,” Hughes said. “People either think he’s off his rocker or they get a kick out of it. It keeps us laughing, which is good because it is a long day.”

City officials also are working to keep the shoppers happy. Martin said city officials had agreed to let all passengers on the T, the city’s public transportation system, ride for free on Thursday.

“It should be a nice opportunity for people to come downtown and do some shopping and not have to worry about finding a place to park,” Martin said. “We’re hoping that it will show people how easy it is to catch the bus and do some shopping downtown on any day.”