The Chorus of Westerly will present its annual summer pops concert Saturday in Wilcox Park.

For an event that wasn’t supposed to be anything more than a one-shot deal, Westerly’s annual summer pops has turned out to be a sure-fire tradition.

This is the 28th year for the popular outdoor concert, which draws an estimated 25,000 fans from across the region. Starting tomorrow at 5 p.m., legions of spectators will be allowed to begin the mad dash to stake out territory in Wilcox Park, spreading blankets on the grass to reserve a spot for Saturday’s free concert.

“Half the time, by eight in the evening, you can’t see grass,” said organizer Doug Rayner. “It’s all covered with blankets.”

The show, highlighted by a performance of the 1812 Overture that’s complete with a Grucci fireworks display, cannon fire and clanging church bells, is put on each year by the Chorus of Westerly. But it was never intended as a tradition, said Rayner, a chorus board member who helps oversee the annual event.

That first show, back in 1981, was meant as a thank you to the town for supporting the chorus on a tour of Great Britain. It was supposed to be a one-time event, and that was it.

But townsfolk felt differently, and began demanding an encore performance the following summer. The chorus had little choice but to oblige.

“Twenty-eight years later we’re still doing something we were supposed to do once,” said Rayner, “and I’ve become an old man in the process.”

At first, concerts were held on the Post Office steps, with spectators spilling out into the downtown. But the crowd became so big, people couldn’t hear or see what was going on. So the event was moved to nearby Wilcox Park, which offers 18-acres of open rolling greenery.

Now it is an institution locals would not think of missing. Rayner said people come from across the region. For years, a couple from Pennsylvania attended on a regular basis.

“They got stuck in traffic one year, and came into the park to see what was going on,” said Rayner, a retired physician. “They even ended up helping us pick up trash after the show.”

Local businesses get into the act. A lumber yard donates the materials for the massive 55-foot square stage, with a carpenter who belongs to the chorus heading up a group of volunteer builders. Pizza, hot dogs and soft drinks are sold by the Westerrly Rotary Club, which contributes all profits to the effort.

Donations also come from the town and individuals. The price tag for this year’s show, a break-even proposition, is about $80,000.

And a waste-hauling company donates time for the clean-up, which begins the moment the show ends and continues into the wee hours. The objective is to dismantle the stage and return the park to normal by noon the following day, said Rayner.

“It’s a huge project,” said chorus director George Kent.

“It’s an outing for the town. And for us it’s a good way to expose people to music they may not be subscribing to. Maybe it will perk them up and they will come to hear Beethoven.”

Although food is sold on the grounds, a lot of people bring picnic dinners, often with elaborate fixings. The show is as much a social occasion as it is a concert, said Rayner.

But there is plenty of opportunity to enjoy music.

A pre-show program featuring jazz, Celtic fiddle music and folk dancers starts at 6:30 p.m., with the main event following at 8. This year, Kent has picked music from South Pacific, which is big on Broadway right now, the theme from the Indiana Jones movies and John Williams’ Olympic Fanfare, a tribute to the summer Olympics in Beijing.

Soprano Megan Besley, who took part last year in the chorus’ 500th performance, returns with a group of standards by Cole Porter and Rodgers and Hammerstein.

“I’m not up on the current Tina Turner stuff,” said conductor Kent. “That’s not my bag.

“What we do are oldies but goodies, the kind of music with the nice changes.”

Kent will be leading his 200-voice chorus and an orchestra of about 52 members, players from Boston and Rhode Island, along with old school chums from as far away as Florida.

“You can’t do pops with less than that,” he said. “If you don’t have triple winds you start getting into not so great charts.”

Kent and Rayner are of course praying for good weather. If it should rain Saturday, the concert will take place Sunday night. And if Sunday is a wash out, it will be rescheduled for Monday. If it doesn’t take place by then, said Rayner, “we quit.”

But in 28 years, the event has never been cancelled, even though a couple of times it has had to be postponed until Monday.

“I’m past the point of worrying about it,” said Kent. “We just go with whatever happens.”

Again, the concert is free. Call (401) 596-8663 for information.

cgray@projo.com