And it's not just the motels and eateries that prosper.
"We'll probably use between 5,000 and 6,000 head of cattle," Kemp said. "They come from the Valley feedlots, and we'll spend upward of $120,000 for them."
As big a boon for the Valley as the event is, it's a shame more people don't know about it, Kemp said.
"We'd love to have more spectators," he said.
Admission is free and competitors are friendly, happy to stop and talk about their sport.
"We'll even let kids come up and pet the horses, if they ask first," he said.
Cutting horses are a special breed of quarter horse, explained Brawley's Ross Jenkins, president of the Pacific Coast Cutting Horse Association and a director of the National Cutting Horse Association.
The object is for the horse to keep a cow separated from the herd.
"It's reins-free work," Jenkins said.
The rider leads the horse into the herd and "cuts" out one particular cow. When the rider is ready for the horse to take over, he drops the reins. The horse is then on its own.
"The rider can't use his hands," Kemp said, "only his feet."
The horse, meanwhile, turns left and right, following the cow in front of him.
"The cow wants to get back to the herd, and the horse won't let him," Kemp said.
"When the horse mirrors the turns and moves of the cow, it's beautiful to watch and he gets a better score," he added.
The horses get a workout, Jenkins said.
"There's a lot of accelerating, stopping and going."
Riders are given two and a half minutes to score points. The size of the herd depends upon how many are entered in a class.
There are three cows for each horse, so if there are 10 horses entered in the class, the herd is 30 cattle strong.
Competitors cut at least two cows during their run and most times three. Judges then score the horse's performance.
There are a number of different classes, based on the age of the horse. In each class there are two divisions — one for professional horse trainers and another for amateurs.
"We have quite a diversified group of riders," Kemp said.
There are doctors, lawyers, investment bankers and business owners competing.
Many compete themselves, while others hire professional trainers to work with their animals.
Former San Francisco 49ers quarterback Joe Montana has eight cutting horses and sometimes shows the horses himself. Former Pittsburgh Steeler Mel Blount also owns cutting horses, as does professional golfer Hal Sutton.
"It's really a family sport," Kemp said.
Participants as young as 9 and 10 are competing. There also are a lot of teens and college-age youth participating,
And there are a lot of older riders, too. Dave McGregor of Santa Ynez is 78 years old and is in the Valley with his daughter and granddaughter. McGregor and his daughter both are riding this week.
Riders come from all over to compete in the Valley's event. Jenkins noted there are competitors from Texas, Wyoming, Colorado, Utah, Washington, Oregon, even British Columbia, Canada, not to mention California, Arizona and Nevada. There also are a number of foreign-born competitors.
Kemp noted there are twin brothers from Portugal who are professional trainers. There also are a number of trainers from Australia, including Joe Montana's, who came to the U.S. when he was only 16.
Jenkins is one of only a few Valley cowboys associated with cutting horses. Another is El Centro's John Burgun, who came here from Australia. A former professional cutting horse trainer, Burgun now crafts saddles and sells them worldwide.
"I hope to get back competing maybe next year," Burgun said.
Holtville's Howard Smithers is involved in the sport but there aren't many others locals competing. One reason is the Valley's climate in July and August.
"It's hard on both the horses and the cows," Kemp said.
He noted riders usually have to get up at 2:30 a.m. to practice and quit at sunup to avoid the heat.
Jenkins still finds time to train his horses during the summer, though.
"We send them somewhere else," he said, noting he travels to Temecula to train his horses during the summer.
But right now the weather in the Valley is wonderful for cutting horses.
"This is the biggest cutting horse show in Southern California," Kemp said of the Imperial Valley event.
Over the weekend, about 280 riders each day competed in one of two arenas at the fairgrounds.
Competition will continue from 8 a.m. to 9 p.m. all week through Saturday.