Steve Knowlton has run many long races in his life, including 43 marathons and two ultra marathons of more than 50 miles. But the distance he covered in those runs pales in comparison to the one he'll undertake next month.

Knowlton, who lives in Prior Lake, Minn., will set off from Seattle on Aug. 1 for a 4,000-mile cross-country trek he hopes to complete sometime in November, passing through 14 states on the way to his finish line in Key Largo, Fla.

Aside from embarking on the biggest adventure of his life, Knowlton, who will celebrate his 45th birthday during the run, has a bigger purpose: to bring attention to Crohn's disease, an illness that struck him when he was a healthy teenager. Crohn's, along with the related disease colitis, affects nearly 1 million Americans, according to the Crohn's and Colitis Foundation of America.

He has collected $750 in pledges so far through his website at www.knowltesrun.com, but Knowlton hopes to raise $100,000 toward finding a cause and cure for the illness in which bacteria attack the intestines and digestive system.

Knowlton has always been an athlete. He played basketball and ran track at Prior Lake High School. He ran his first marathon when he was 13, and running became a passion.

It was in the summer of 1983, before he started his freshman year at Golden Valley Lutheran College, that his symptoms first appeared. In a matter of five months, he dropped from 180 pounds to 132.

He thought it was nerves, but then one day while running up hills during basketball conditioning practice he felt excruciating pain and doubled over. He was diagnosed with Crohn's, an illness he had never heard of. Shortly after, renowned University of Minnesota physician John Najarian performed surgery and removed eight feet of his intestines.

Knowlton, now a self-employed carpenter, was back running marathons a few years later, but he never talked much about Crohn's. When he tried to explain his surgery, "I always said it was for an appendectomy." Things like "breast cancer are well known, but I was embarrassed of this disease."

He got over that after learning that famous people such as Mike McCready, lead guitarist for the rock band Pearl Jam, and actress Shannen Doherty of "Beverly Hills 90210" have the malady. He wanted to do something to bring the illness into public consciousness and find a cure.

He got the idea of running across the country from Peter Jenkins' book, "A Walk Across America," which he read as an eighth grader.

"I thought doing something like this would bring more attention to it," he said. People need to know "that if you get the disease, you are not damaged goods. You can still accomplish great things."

He's been training for nearly a year for his upcoming run. His plan is to run 40 miles a day, even if it means breaking the daily distance into two sessions of 20 miles each or stopping in an occasional grocery store to get Gatorade, eat or rest.

"I'm excited because that will push me to the limit," he said. "It will take character to endure and the discipline to live up to my word (to run every day). I know I can do it."

Knowlton will push a stroller filled with provisions, such as water, energy bars and extra shoes. His route will take him from the Pacific Northwest through a sliver of Oregon and Idaho and then the Rocky Mountains in Wyoming and Colorado. From there, he'll stride across Kansas and Missouri, then continue east and south through Kentucky, Tennessee, Mississippi, Alabama and Georgia. He'll finish by crossing the Florida panhandle and running down the eastern coast of the Sunshine State.

"I'm looking forward to seeing the beach there."