NEWBURYPORT — As drivers sat still on the Merrimac Street on-ramp to Route 1 south, Michael Vetrano found a silver lining in the regionwide gridlock brought on by yesterday's accident and gasoline spill that shut down Interstate 95 for most of the day.

Vetrano, who owns Newburyport Trolley Company, was unable to navigate his tours around the traffic jam yesterday, so he got creative. For more than two hours, he and his son, Mike, sold water for $1, jumbo ice creams for $2 and big bags of Boston Red Sox peanuts for $3.

"We figured we're sitting here so we would bring (water) to them," Vetrano said. "People were (ticked off), for lack of better words."

He found plenty of eager consumers, including one woman who said she'd had surgery in Boston and sat in traffic for five hours. She got a free water.

"She had just left a hospital in the Boston area and was clutching her stomach where she had surgery. There were two children in the car with a puppy and her husband was driving," Vetrano said. "She asked for a cup with a lid, and I gave her two waters and helped her on her way."

The traffic, caused by a multi-car accident involving a gasoline tanker that spilled thousands of gallons onto the roadway, not only affected I-95 but also many areas surrounding the Newburyport area. While those on the highway slowed to a crawl, side roads around Newbury, Newburyport and Salisbury quickly became clogged as well.

Yesterday afternoon, it took an hour to get from downtown to the I-95 on-ramp at Scotland Road. Stalled drivers and passengers looked out of sunroofs, trying to see how much farther they had to go. Angry motorists leaned on their horns in protest as others swerved around traffic — driving off the road to beat out other vehicles, causing a few fender-benders in the process.

Some of those stuck in the traffic found themselves making their way to Colby Farm to use the restroom and buy a cool beverage. Lisa Colby said that they were selling water, soda, bags of chips and homemade cookies to travelers caught in the traffic.

"I've never seen anything like the line of cars on Scotland Road. I had one person tell me they had been on (the road) an hour and a half, inching along," Colby said. "I feel so sorry for these people."

Traffic on Route 1 backed up in a number of spots between Salisbury and Rowley. High Street in Newburyport was a line of cars. Merrimac Street backed up from Route 1, where Marshal Thomas Howard directed traffic for a time, back to Amesbury.

In Salisbury, police Chief David L'Esperance said traffic was the worst in Salisbury Square. L'Esperance said he had to call in eight off-duty police officers for backup yesterday morning.

"All area departments worked well together; we had Seabrook and New Hampshire State Police helping," he said. "We had guys in Newburyport at the intersections to redirect traffic."

With the highway closed for nearly eight hours, northbound traffic was redirected onto routes 113 and 1. Southbound traffic, which was redirected onto Interstate 495, backed up for nearly 9 miles into New Hampshire.

After the accident first occurred, stranded drivers in the northbound lanes of I-95 pulled dangerous U-turns, driving into the grassy median and across the highway to get on their way.

Working the counter at Famous Pizza on High Street, Sarah Nearis said that making deliveries to the Turkey Hill and downtown areas was difficult, though walk-in business was up. But not everyone wanted food.

"To be honest, in the past couple of hours, there have been more people asking how to get to Water Country or other places because they can't use I-95," Nearis said.

Denise Weir, owner of Denise's Flower Shop on Pleasant Street, said that traffic hadn't affected her deliveries too much because they knew the back roads.

"When you know the back roads and middle roads, it makes all the difference in the world," Weir said. "We know how to sneak."

Weir said that there had been no cancellations of orders, but she said there was a positive side to all the traffic.

"There are people coming off the highway coming down to Newburyport to shop," Weir said. "It's brought in business to Newburyport, so there's a bright side to everything."

Staff writer Katie Curley contributed to this report.