The first big holiday of the warm-weather tourism season slowed southbound traffic Monday afternoon on the Maine Turnpike.

Traffic began building in the late morning, and by early afternoon had caused a slowdown that stretched from the New Hampshire border, through the York tollbooths to the Ogunquit on- and off-ramps.

At the York tollbooths, the traffic count peaked at 4,200 cars between 11 a.m. and noon, said Duane Douglass, toll supervisor. It had thinned to about 3,500 cars at the 3 p.m. count, and was back up to 3,700 by 5 p.m.

“When it hits 4,000, that’s about as much as (Interstate) 95 can handle,” Douglass said. “When it hits 4,000, that’s when you find an alternate route.”

By 6:30 p.m., the traffic flow had returned to normal.

Contrary to some beliefs, the traffic issue is not related to the York tollbooth, Douglass said. “We move traffic through here so fast, it backs up from the high-level bridge at the state line right up through the tolls. People slow down when they go up over the bridge, and it just hits a saturation point,” he said.

At least one motorist confirmed that observation.

“We were slowed down to 10 to 20 (miles per hour) from maybe three miles before the tolls, and were very disappointed to see it was no better when we got through them. It didn’t start to get better until we crossed the bridge at the border,” said Vicki Lloyd, who lives 40 miles southwest of Boston.

She spent the weekend at an island in the midcoast and left for home around 1 p.m. What normally would be a 3½-hour drive took nearly five. During future weekend visits, she said she would consider spending an extra night and driving home early the next morning.

Staff Writer Bob Keyes can be contacted at 791-6457 or: bkeyes@pressherald.com

Twitter: ppbkeyes