West Tisbury businesses, from a gas station to farm stand vendors, fear that the partial closure of South Road and prominent detour signs spurred by President Obama’s visit will hurt sales during one of the busiest weeks of the year.

President Obama arrived for a nine-day visit on Martha’s Vineyard last Saturday. The first family is staying at a private home off South Road in Chilmark. Because of security concerns, South Road is closed between Meeting House Road and Wooton Bassett Road until August 18.

Large neon detour signs are in place, including in front of the West Tisbury fire station and at the intersection of Edgartown-West Tisbury Road and State Road. The signs warn that the road is closed ahead and advise vehicles to take a North Road detour. Signs are also in place along State Road in North Tisbury, directing traffic off State Road and toward Menemsha.

But a handful of West Tisbury businesses situated between the detour signs and the road closure say the traffic change will keep people away from the village center at the very height of summer and the week of the Agricultural Fair.

“We are very impacted by this,” said Andrea Rogers, manager for the Vineyard Artisans Festivals, which take place Thursdays and Sundays at the Grange Hall. More than 70 artists sell ceramics, jewelry and art at the festivals.

“August is our make it or break it month, so this is the worst possible time of the year to block access,” she added. “It impacts a lot of people.”

Already, Ms. Rogers said, there were fewer people at last Sunday’s festival. She said the signs make it seem that people have to turn right, away from the downtown area, and that the signs are especially confusing to visitors.

“I know they have to do what they have to do,” she said. “I understand the way the world works. I just feel it could have been done a bit differently.”

“We’re really in a bad position at a critical time of year . . . we’re trying to survive the winter.”

In West Tisbury Tuesday, the scene appeared normal for a rainy summer day. There were lines for newspapers at Alley’s General Store and breakfast sandwiches at 7a foods.

But those coming from down-Island passed a large sign warning of a road closure three miles ahead, Detour signs pointed away from the town center. Outside the town hall, a big yellow bus carrying the press pool was swept by an agent with a black dog.

Chris Scott, executive director for the Martha’s Vineyard Preservation Trust which owns Alley’s, said he anticipated a 25 per cent loss in gross sales for this week over last year.

“The parking lot is full of empty spaces – it’s August and it shouldn’t be,” he said. “For this week in August, it’s a very big hit. It’s the busiest week of the year. If the season is 100 days, a week is very significant.”

“You don’t get this week in August back for a year,” he continued. “That’s what happens when you take the major east/west corridor and turn it into a dead end.”

Mr. Scott said it’s “been a challenging summer in general.” He partially attributed this to attributed it partially to renovations of the library located across the street; during construction, the library has moved temporarily to North Tisbury.

As she stacked plums and sorted produce at Alley’s Farm Stand, Alley’s General Store manager Rhonda Backus took a more sanguine view. Delivery trucks, originally hesitant, have figured out the detours, she said, and she said it seemed business hadn’t been greatly affected during the first few days of the road closures.

“It’s been a really good summer,” she said. The store is a nonprofit and open year-round. “This is the busiest week. This is when we make our money.”

“I think people do love Alley’s because it’s been here so long,” she added. On Saturday, the president’s arrival brought a crowd to the famous front porch at Alley’s to greet President Obama.

“It’s nice that the magic hasn’t faded,” Ms. Backus said. She took a break from work Saturday to watch the motorcade drive by and encouraged her staff to do the same, telling everyone to clear out of the store.

“It’s really special that the president of the United States lives around the corner and comes by,” she said.

A few years ago, the president and his daughters visited the store. Employee Maya Sharp recalled that the Obama girls bought candy and astronaut ice cream.

This year, “I would love it if he came by. I would like to meet him,” she said.

At 7a, chef and owner Daniel Sauer paused while carrying two cans of chickpeas to say he didn’t think the take-out restaurant had been affected.

“We’re still jam-packed,” he said. “Same crowd.”

Mr. Sauer was worried when he saw the detour signs, he said, but “it hasn’t done anything to deter [business].”

The mood was markedly different at Up-Island Automotive, where employee Steve Serusa said business was down. “All the detour signs have taken a hit,” he said as he filled a Tri-Town ambulance with gasoline.

“This is the busiest week of the year,” he added.

“It’s equivalent to our whole February, this one week,” Wyatt Jenkinson chimed in.

The shop placed their own sign by the detour sign on Edgartown-West Tisbury Road, announcing that the gas station is open. Other than that, “there’s nothing you can really do,” Mr. Serusa said.

However, the station has some new business: the presidential motorcade has stopped to fill up.

Kara Taylor Fine Art, located about a mile away from the road closure, posted on Facebook that the visit is definitely causing a lull in her business and urged people to stop by for a picnic in the field.

Down South Road at the Allen Farm Sheep and Wool Company, which is located just past the closed portion, Susan Huck said she thought the shop has seen a little impact, “but you can never be quite sure.”

“We still have had business,” she said, though with the heaviest business coming Thursday through Sunday, the weekend will be the test.

“I’m the one who’s so concerned because it’s my biggest week,” said Linda Alley, the co-organizer of the West Tisbury farmers’ market. She sells her jams at the Wednesday and Saturday markets near the Grange Hall.

On Wednesday morning, she and fellow organizer Rusty Gordon will arrive in town early to place handmade signs around to remind people that the farmers’ market is still open and accessible.

“It’s horrible,” she said. “People are so confused. Other people have mentioned to me about how confusing it is . . . people have asked me, ‘Does that mean the gas station isn’t open?’

“Hopefully, people don’t get baffled.”

Remy Tumin contributed reporting.