NARRAGANSETT — Connecticut high school teacher Christian McEvoy learned a lot running through America.

He found the best places to get coffee — shiny diners and noisy nooks in Iowa, where the cup includes a smile.

He learned about generosity when he blew through St. Francis, Kan., a town of 1,500 on the Republican River. They celebrated his arrival and “threw open their doors” to the runner and his crew.

And he discovered that running for a cause — in this case, cancer research — was easier than he thought it would be.

Although he wore out 35 pairs of shoes and sometimes ran for eight hours a day, the 24-year-old rarely complained.

“It’s amazing what the human body can handle. And it’s amazing what the human spirit can handle,” said McEvoy, who yesterday finished his 3,500-mile trek by leaping into the cold waters off Narragansett Town Beach.

McEvoy’s run helped raise more than $200,000 for cancer groups and survivors, including the Yale Cancer Center, in Connecticut; the Ulman Cancer Fund, in Maryland; the University of California; the San Francisco Cancer Resource Center and The Children’s Hospital HOPE Clinic, in Colorado.

“This is just the beginning,” said McEvoy, speaking inside a tent erected near the beach. Nearly 300 other runners, students and cancer survivors joined McEvoy on his last leg, from Westerly to Narragansett.

Cars jammed the parking lot, making it look like a summer day. Near the entrance to the beach, a crowd cheered as each runner, their backs to a slanting sun, puffed past the finish line.

“A lot of people thought I was crazy, but a lot of people supported me, too,” said McEvoy, who pointed out that his team includes more than 30 people, including a road crew, cancer survivors, events coordinators, several lawyers, a nutritionist, a doctor and a physical therapist.

During his 24-week journey, McEvoy had plenty of time to think about his life and goals — and how things don’t always turn out the way you think.

A Maryland native, McEvoy graduated from Connecticut’s Fairfield University in 2004, and got a job teaching English at a Connecticut prep school.

He was always athletic. At Fairfield, he went from a mediocre swimmer to a recognized leader on his swim team. In 2005, he took 15th place at the internationally competitive Escape from Alcatraz Triathlon. During NBC’s coverage of the 2005 Ford New York City Triathlon, McEvoy was interviewed while biking his way to a first-place finish in his age group.

But his life took a turn when the mother of a good friend was diagnosed with breast cancer.

In a bid to support his friend and his mom, he helped plan a 100-mile bike ride to benefit cancer survivors. A month later, he decided to do the same thing on his own — on a national scale.

On July 1, he put his teaching career on hold and stepped off from Baker Beach, in San Francisco, with Rhode Island as his destination. He called his fundraiser “Coast to Coast: A Run for Survivorship,” and promised to involve high school students and others along the way.

McEvoy ran from three to eight hours a day. For energy, he gobbled 10,000 calories a day, often from Subway sandwiches and Bear Naked granola, food provided by two of his sponsors. He drank bottled water and Gatorade. He changed his Asics shoes every 100 miles, and slept in a touring RV, in hotels and in homes.

“There’s no magic pill to long-distance running,” said McEvoy, a coach and a trainer who has developed running and endurance programs.

You just drink plenty of liquids, keep a clear head, and don’t run when you’re hurt. It helps if you don’t have to worry about a wife, kids and a job, he added. “I thought that mentally it would be much harder.”

Along the way, McEvoy developed a sense of the country — its terrain, its politics and its big-heartedness. Yesterday, the American scenes came in flashes. Kansas wasn’t flat. Colorado wasn’t one big mountain range. In Ohio, McEvoy passed a city zoo filled with lions, tigers and bears. He rushed through small one-industry towns, and passed by street corners where local connections took a back seat to national politics.

“The United States is an amazing country — and a big country,” he said. “I’m not so sure you realize how big it is until you traverse it on foot.”

After nearly a half-year of running, McEvoy yesterday was suddenly still. His hair wet from his plunge in the ocean, he struggled to make sense of it all. “The emotions are too much. I’ve been thinking about this so long.”

On the days he didn’t feel like running, he thought of the 10 million cancer survivors in America. He thought about his best friend’s mom.

And he put one foot in front of the other.

“This is something that really matters to me. I ran across the country for it. If I was running for myself, I wouldn’t have made it.”