ONCE A NICHE SPORT MARATHONING IS NOW BIG BUSINESS

THE BOSTON GLOBE

Passersby hurled beer cans and insults at Neil Weygandt during training runs. In the late 1960s, most people thought he was crazy for wanting to race 26.2 miles. But he liked the challenge and the camaraderie of running marathons. On Monday, Weygandt will run the Boston Marathon for the 44th consecutive year, the longest such streak. Since he started, the marathon has evolved in once-unimaginable ways. Streets cluttered with runners have replaced beer cans as obstacles.

“I do miss the camaraderie among the small numbers of runners,’’ said Weygandt, who first competed in a field of 741. “And there’s so many hassles involved. You have to get up early and ride the bus to the start. I remember driving into Hopkinton. It certainly has changed a lot, but the experience is worth it.’’

Judging from sold-out major marathons and record fields at other marathons, the 26.2-mile race has shed its extreme-sport reputation and entered the sports mainstream. And neither runners nor race directors are turning back.

In the late 1970s and early ’80s, marathoners typically raced for fast times. It was about the competition. Entrants were often distance runners in high school or college. And until women like Roberta Gibb and Kathrine Switzer broke barriers in Boston, the fields were all male. It was a different runner’s world.

“Now, it’s all about participation,’’ said Boston Marathon race director Dave McGillivray. “The walls of intimidation in our industry have crumbled and that started to happen in the ’80s.’’

Today, marathon runners don’t fit a particular profile. They are your neighbors, Hollywood celebrities, lifelong athletes, geeks, grandmothers . . . and the list goes on.

New York Road Runners CEO and president Mary Wittenberg calls today’s marathon fields “the ultimate melting pot.’’ The sport, in part, has legendary American marathoners to thank for that. Frank Shorter’s 1972 Olympic marathon gold medal increased US interest and participation. Joan Benoit’s 1984 Olympic gold inspired women everywhere. Now, marathons are just as much about the everyday runner as they are about the elite runner.

“We’re seeing time and time again that the marathon is the kind of bucket list, almost-impossible-to-achieve goal that gets people motivated,’’ said Wittenberg. “And it acts as a catalyst. Most of the people who are sitting on the sidelines or on the couch look at the race and see someone just like them. That’s a big part of the appeal. They say, ‘It’s something I can do with training.’ ’’

In 1976, 25,000 Americans finished marathons, according to Running USA. Last year, there were a record 467,000 American marathon finishers. With 43,660 finishers, the 2009 New York City Marathon went down as the largest ever. And 20 US marathons topped 5,000 finishers last year.

Running USA also revealed marathon fields have increasing numbers of women (10 percent of competitors in 1980, 41 percent last year) and runners 40 or older (26 percent in 1980, 46 percent last year). But more than that has changed.

The current generation of marathoners run to celebrate surviving cancer or a weight-loss goal. They run for charity, for the memory of a loved one, for a once-in-a-lifetime experience.

“Our sport only lifts people up,’’ said four-time Boston and New York City marathon champion Bill Rodgers. “No one gets knocked back. I’ve met people who’ve lost 20 pounds and are right next to me running seven-minute miles. At a race in Missouri, I met a woman who had lung cancer, who had surgery, chemotherapy, and now she’s doing a marathon. What? Marathoners are redefining what it means to be an athlete.’’

And they have plenty of opportunities.

This weekend, 10 marathons besides Boston will take place around the country, from Cumberland, Md., to Willard, Mo., to Wenatchee, Wash. There is even the inaugural Exeter Marathon in Rhode Island, organized for runners shut out of Boston. Exeter boasts qualifying times five minutes faster than the ones required by Boston. And race director Michael Tammaro reported eight of 60 entrants plan to run Exeter tomorrow and Boston on Monday.

Every race has a hook now, something that sets it apart on the crowded race calendar. Some races promote scenic beauty, some mile-by-mile entertainment, some flat, fast courses, some postrace food offerings. Many marathons are as much a social event as an athletic event. Chicago Marathon executive race director Carey Pinkowski views the ever-increasing number of marathon runners as a “social phenomenon,’’ a marked contrast to the days when people talked about the loneliness of long-distance running.

“It was a competition 21 years ago,’’ said Pinkowski of when he took over as race director. “Now, there’s so many other facets. We spend as much time outside the curbs as we do inside the curbs.’’

Or, for runners in the Walt Disney World Marathon, that would be outside and inside Cinderella Castle as the course tours various theme parks. At the Marathon du Medoc in France, participants are encouraged to run in costume and linger at the water/wine stops. Several New England marathons use fall foliage as a draw. There are marathons for runners of all different tastes and speeds.

“It’s a constantly evolving event and it’s all about the experience,’’ said Wittenberg. “We don’t want anyone going to any marathon anywhere and being bored.’’

When the New York City Marathon moved to the streets in 1976 with 2,000 runners, Wittenberg said “it changed everything’’ for the event because of the citywide spectacle it created.

The spectacle has come to define the mass of runners, the throngs of spectators, and their interaction. Runners can be part of a spectacle in a way that’s not possible with mainstream professional sports.

“The majority of people who participate in a marathon today are running against themselves,’’ said McGillivray. “They cross the finish line. They go home feeling good about themselves. It’s all about self-esteem. That’s what’s driving this industry right now.’’

There’s no telling where such a powerful force will take marathons in the future. But Rodgers and the race directors of major US marathons see a long way to go with more runners joining the spectacle.