When George Carlin grew his hair out, toured college campuses and coffeehouses, and began performing countercultural material in the early 1970s, he was forging a reputation for irreverent social commentary that would make him one of the best-loved comedians of all time.

But Carlin, who died on Sunday in California at the age of 71, was an upstart in other ways. For stand-up comics who had depended on appearances on network television to find financial success, he blazed a new path in finding audiences and in touring, always touring.

Today "the live venues are the real bread and butter of a comedian's revenue stream," says Andrew Alexander, owner and executive producer of the Second City, a training center for sketch comedians with locations throughout the United States.

Carlin "probably was making over $5 million a year, very quietly," estimates Caroline Hirsch of Carolines on Broadway, the comedy club where countless stand-up comedians have come up through the ranks.

He made that money not through movie deals or TV shows, but a steady routine of writing and performing material. "No one was as prolifically evolved as he was," says Hirsch. "That man writes a new show every year."

That level of achievement looked far from certain back in the late '60s, when Carlin told his managers and agents that he wanted to go open for rock bands and perform for college students.

"He put his career at risk. It was a very brave thing for an artist to do," says Richard Zoglin, a writer for Time and author of Comedy on the Edge: How Stand-Up in the 1970s Changed America.

Of course, Carlin was not always a renegade, and he did perform on some comedy-circuit staples. In the '60s and '70s, he appeared regularly on The Merv Griffin Show, The Ed Sullivan Show, and The Tonight Show, making a name for himself and building the audience of fans that would flock to see him live.

In 1975, he hosted the first-ever broadcast of Saturday Night Live, the sketch-comedy show that would go on to make the careers of scores of young comics.

And throughout his career, he released comedy albums and taped HBO specials that expanded his reach to new audiences across the country.

In the 1980s, starring roles on sitcoms became the standard pot of gold for stand-up comics like Roseanne Barr, Bill Cosby, and later, Jerry Seinfeld. Carlin belatedly joined the wave with The George Carlin Show on Fox in 1994. His attempt to join what he called the "corporate entertainment structure" lasted only one season.

Movies, similarly, held little appeal for him. Other major comedians, like Robin Williams, Steve Martin, and Billy Crystal, says Zoglin, "all used TV and movies, and that made them hot draws on the concert circuit. Carlin was hot even without that other stuff."

Zoglin says that comics able to mobilize those kinds of loyal fans without a similar "boost" are rare today.

One comic of a younger generation, Dane Cook, for a while seemed to be making a bid in that direction, with his Carlin-like focus on releasing comedy records and persistent touring. Cook famously established himself via the social-networking website MySpace, where he built a fan base of young people much the way Carlin did by performing at colleges and rock concerts.

Carlin had an instinct for making his brand of humor profitable without turning himself into a bland, mainstream movie star. Perhaps that was the most countercultural choice—more than swearing on live television, admitting to substance addictions, or growing his hair long—that he ever made.

Says Alexander of the Second City: "George Carlin was such an extraordinary social behavioral comedian that he kept relevant, and had an acute sense of how to translate that into funny."