(FORTUNE Magazine) – Funny business is booming. In the past decade scores of comedy clubs have opened in the U.S., which is good news for frazzled business travelers. As a diversion, comedy is usually less expensive than the theater or symphony and easier to walk out on. It can also be enjoyed libation in hand. Television created the demand, especially such programs as Johnny Carson's Tonight show and Late Night With David Letterman, which offer young comics the chance to make fools of themselves. Through their monologues, Letterman and Carson also established the predominant style of the Eighties. Rather than the old joke-with-punch-line format, it relies on a wry commentary on the day's events, public or private, along with the misadventures of growing up. In clubs, however, the routines are longer, more spontaneous, and more pungent with drugs, sex, and scatology than anything on TV. Masters of the art practice it in a variety of styles. Jay Leno's blue- collar, guy-next-door musings on the exigencies of cut-rate airlines and obtuse tradesmen have made him the favorite performer on the comedy club circuit. Close behind come Steven Wright, known for his tortoise-paced delivery and nonexistent smile, and Emo Philips, whose semispastic locutions and grotesque sartorial tastes place him firmly in the court jester tradition. There are also comics who ramble funnily along while doing magic or juggling. Clubs generally seat 150 to 200 people and fall into two categories. Headliner clubs have a set show time and feature three acts of roughly half an hour each -- an opener, a middle act, and a headliner. Showcase clubs typically present new talent, though those on the coasts are more often showcases for established comedians vamping in front of network talent- spotters; acts follow one after the other until boredom or the local liquor laws send the patrons home. Most places devote one night a week to ''open mike'' nights, when nascent Lenos and Wrights get up for ten minutes in search of glory. Open-mike nights tend to bring cover charges down to no more than a couple of dollars. Otherwise tabs range from $4 to $6 weeknights to $8 to $12 weekends, sometimes with an additional two-drink minimum. A special headliner can push prices toward $20. Though many clubs are open seven nights a week, many are not; phone to elicit the latest information. All take major credit cards unless otherwise noted. Perhaps the most surprising comedy club boom has been in the South. Much of the credit goes to three young entrepreneurs who opened the Punch Line in Atlanta in 1982. Since then they have opened nine more in other Southern cities, all following the same format. The headliners are usually graduates of Letterman and Carson, and in Atlanta, at least, the New South audiences are savvy. Canadian comedienne Lois Bromfield strikes the right note when she sarcastically says, ''I love Beverly Hills because the people are so real and down-to-earth'' (280 Hildebrand Drive; 404-252-5233). The others, all but one under the same name: Jacksonville, Florida (904-737-9399), Tampa, Florida (935-4746), New Orleans (504-454-7973), Mobile, Alabama (205-479-5653), Montgomery, Alabama (205-277-3866), Birmingham, Alabama (The Comedy Club, 205-942-0008), Greenville, South Carolina (803-235-5233), Columbia, South Carolina (779-5233), and Charlotte, North Carolina (704-552-1744). ''I became a doctor because I like jewelry and sports cars, and I became a comedian because sick people are depressing,'' says physician-turned-comic Bill Miller. It's the sort of thing the blase audience at the Laff Stop in Houston's drop-dead River Oaks section wants to hear. Rib-tickling jugglers, hypnotists, and magicians also headline in this 300-odd-seat room (1952-A West Gray Street; 713-524-2333). The Funny Bone, a 30-minute drive from downtown St. Louis, is another stop on the Jay Leno-schlepped-here circuit. A regular emcee is St. Louis radio personality Al Richardson, who will regale patrons closest to the stage with remarks such as, ''Ever been this close to a black man before?'' (734 Westport Plaza; 314-469-6692). The largely suburban audiences at the Cleveland Comedy Club don't mind jokes about their city. ''I'm glad to be here,'' says Ollie Joe Prater as he begins a relaxed and raunchy performance. ''But then last night I was in jail in Nashville.'' The club is a slightly seedy room lined with hundreds of post- card-size reproductions of the Mona Lisa wearing every variety of leer and grin except her famous smile. The seats at the back are the best for bar service and are a safe distance from the stage (2230 East Fourth Street; 216-696-9266; no credit cards). There is no safe distance from the stage at the relentlessly sophisticated Byfield's in Chicago's Ambassador East hotel -- 80 patrons can be squeezed in with a push. Satire is popular, especially when provided by Chicagoan Aaron Freeman. ''If men got pregnant, abortion would be a sacrament,'' he told an audience not long ago. Byfield's also books classic comedians like Mort Sahl (1301 North State Parkway; 312-787-6433; closed Sunday and Monday). Zanies, in Old Town, is the Second City's primary showcase, though it also attracts headliners such as Emo Philips. Former Chicago rock-and-roller Skip Griparis is a regular, with hilarious impersonations of singers from Desi Arnaz to Bruce Springsteen. Local artists provide acerbic insights into the byzantine dealings of Chicago's politicians (1548 North Wells Street; 337-4027; closed Monday and Tuesday). The polite audiences at Seattle's Comedy Underground in the Pioneer Square district laugh in the right places and answer the headliner's questions without trying to be overcute. The headliners are nearly all from the Carson- Letterman stable (222 South Main Street; 206-628-0303). San Francisco's Holy City Zoo attracts experimenters and comics with new material; Robin Williams of Mork & Mindy fame made his debut in an open-mike session here, and he returns sporadically to try out new madness before exposing it to the airwaves (408 Clement Street; 415-386-4242). Among the predictable targets at Boston's Comedy Connection are academic matters, nuns, Jesuits, and the Hub's way with the a vowel sound. ''I was passing MIT and got attacked by an irrational number,'' says a dour, open-mike comic. Steven Wright made his debut here; a current favorite is Kevin Meaney, who recently won an Emmy for his improvisations of celebrities' dogs: James Stewart's barks with a stammer (76 Warrenton Street; 617-391-0022; no credit cards).

Despite the spread of new clubs, New York and Los Angeles remain the busiest venues for comic entertainment. Among the standouts in New York is the Original Improvisation, which opened in 1963 as a hangout where young performers such as Richard Pryor and Lily Tomlin could polish material before taking it to Las Vegas or the TV networks. Rodney Dangerfield still pops in to work on a new routine (358 West 44th; 212-765-8268; no credit cards). Like the Improv, Catch a Rising Star has a public bar in front where sad- faced comedians lurk before their sets. On stage they take aim at apartment rents, Central Park after dark, and Long Island housewives who don't like to break their nails. Catch audiences are tolerant of esoteric material; they even laugh at existential comic Gilbert Gottfried's rapid-fire, nonjoke jokes: ''What did the gorilla say when he came into the bar? I don't know. If I saw a gorilla in a bar, I'd get the hell out.'' Alumni who went on to fame in funnydom include Billy Crystal of the TV series Soap (1487 First Avenue; 794-1906; American Express only). The clubs of Los Angeles range in character from dim beer-only bars to sophisticated Hollywood warehouses stuffed with celebrities and nonstop comedy. The Laugh Factory is the only one of the latter that offers an open- mike night (Tuesday); Mark Price of TV's Family Ties was discovered in such a session (8001 Sunset Boulevard; 213-656-8860). The Comedy Store is the largest operation of its kind in the U.S. Celebrities appear in the 400-seat Main Room; some 30 lesser comedians perform each night in the 225-seat Original Room (8433 Sunset Boulevard; 656-6225; Visa and MasterCard only). But if you have only one night to laugh in L.A., the Los Angeles Improvisation is the place to spend it. The nationally syndicated An Evening at the Improv has made the place familiar to millions: The performers could fill a comic's hall of fame; the bar is one of the trendiest show biz spots in town. Talent-spotters are omnipresent, which means that comedians have to work harder for laughs here than anywhere else in the country (8162 Melrose Ave; 651-2583).