For 20 years, the Rennison family of Grahamsville has been serving kettle corn to concertgoers at Bethel Woods, beginning with a sold-out Crosby, Stills, Nash & Young show during the venue’s first season.

Jim Rennison said What’s Poppin’ Kettle Korn was Bethel Woods’ first outside vendor and has been there ever since.

Their first night nearly created a problem.

The line for kettle corn grew so long that it began blocking people entering the show.

“[Bethel Woods founder] Alan Gerry saw that, and from that time on Alan said, ‘I want these guys for every show,’” Rennison recalled.

Gerry moved the stand closer to the lawn, where customers could wait in line while still watching the concert. He also allowed What’s Poppin’ to keep its distinctive tie-dye tent while other vendor tents were white.

The Aug. 13, 2006, Crosby, Stills, Nash & Young show drew more than 16,000 guests.

Rennison had started What’s Poppin’ two years earlier while preparing to retire from his job as a correction officer.

He got the idea after watching a cousin find success selling kettle corn in Rhode Island. Jim and his wife, Melissa, began working small street fairs before moving into larger venues. When Bethel Woods opened two years later, Jim called and asked for a chance.

The kettle corn itself also took some experimenting.

Rennison said he chose corn oil from the beginning, even though it cost more than oils commonly used by other kettle corn vendors. He had been advised that the difference in flavor could help his product stand out.

From there, he adjusted the amounts of oil and sugar from batch to batch.

“I started tweaking my recipe,” Rennison said. “Add a little bit more corn oil, a little bit more sugar, until people in front of me started saying, ‘This is the best kettle corn I’ve ever had.’”

Once he started hearing that regularly, he stopped changing it. The same recipe has remained in place ever since.

Shane Rennison was six when his parents started What’s Poppin’ and spent much of his childhood working alongside them at fairs and concerts.

“To me, it was so normal,” Shane said.

He learned to count money and deal with customers behind the stand while growing up within earshot of some of the biggest names in music.

Now a full-time musician, Shane remembers watching Eddie Van Halen’s hands on the video screens and seeing Carlos Santana perform about 100 yards away as he helped his family serve kettle corn to guests.

“You’re surrounded by your environment,” he said. “When I did go into music, just naturally, you’re going to be pulling from your experience as a kid.”

For Jim, now 65, Bethel Woods remains at the center of the business.

“It’s our golden nugget,” he said. “We’re basically family.”