LAS VEGAS

ALONG traffic-choked Las Vegas Boulevard, stretch limos deposit tuxedoed entertainers beneath the marquees of palace-sized casinos: Stardust, Sahara, Riviera. Inside, masses of people in caps and sweat shirts - 28 million last year - feed quarters into acres of slot machines 24 hours a day.

Five miles north, just blocks from downtown City Hall, a group of homeless men warm themselves on refuse burning in a steel drum. One wears a cardboard sign: ``Will work for food.''

Farther out to the northwest, potential home buyers ogle a lighted model of the largest master-planned development in the United States, Summerlin. Already boasting thousands of young families and retirees, the sprawling community includes libraries, civic centers, work-out clubs, malls, and six golf courses carpeted over sandy soil.

Metropolitan Las Vegas, a mere desert crossroads of 5,100 the year before the state legalized gambling in 1931, has outpaced the growth of every other American city for six decades. It is still the fastest-growing city: an even million at last count, with plenty of room amid the saguaro for more. With that increase have come the growing pains of large populations - traffic congestion, smog, crime, homelessness - but also the opportunity to reinvent itself.

``We're graduating beyond gambling and flesh shows,'' says Mike O'Callahan, former Nevada governor and now executive editor of the Las Vegas Sun. Twenty years ago, touring Russian cosmonauts refused to enter Nevada because of Las Vegas's reputation as ``sin city.'' Today, says the 40-year resident, ``I tell you there are more lights on softball fields than casinos.''

In the past five years, city fathers have orchestrated a formalized effort to cast off the town's time-worn image as the world's playland getaway and redefine itself both as a family-oriented tourist destination (Article, right) and an all-American city. That has meant a stronger civic focus on theater, music, ballet, and schools for its own residents. It has also meant a full-scale push to diversify business, upgrade educational institutions, and remake infrastructure from water to highways, mass-transit, and even sewers.

``The press comes in here and all they write about is the [casino gambling] strip,'' complains Mayor Jan Jones, pointing south from her 10th-floor downtown office.

Last year, the opening of three major casinos - adding more hotel rooms at one intersection than exist in all of San Diego - made headlines worldwide. But Mayor Jones points north to miles of new, orange-tile-topped developments and touts the highest percentage of churches, synagogues, temples, civic organizations, and children's leagues of any US city. ``Why don't they write about this as well?'' she asks.

The Las Vegas of gambling and the Las Vegas of homes and families in fact enjoy a symbiotic relationship. Casinos brought in $6 billion last year, funding more than 43 percent of Nevada's general fund. That offers businesses and citizens alike a life with fewer taxes, cheaper housing (median cost: $126,000), and lower cost-of-living than neighboring Arizona, Utah, and California.

``Lower taxes, lower workmen's comp, lower labor, utility, and occupancy costs typically add up to 30 percent lower cost in doing business here [than California],'' says Dennis Stein, president of the Nevada Development Authority. He hands visitors a list of 50 companies that moved to the area last year, 70 percent from California. Names include Ocean Spray Cranberries, Big O Tires, and Household Credit Services.

``We wanted to grow in a regulatory environment that was pro-business and would allow us to build and operate at low cost,'' says Household Credit Service's Mike Walter. ``And we needed a good source of qualified labor - we found all three in Las Vegas.''

Drawn by the allure of mountain vistas, sunshine, and a lower cost-of-living, 4,000 to 6,000 people a month are packing into the sage-encrusted landscape here. To accommodate them, cookie-cutter developments now ring the city with names like Cherry Creek, Willow Tree, and Vista Del Oro.

``Las Vegas may be the last million-plus metropolis of the Sun Belt for decades to come,'' says California historian Kevin Starr. Following the same archetype of Los Angeles's sprawling San Fernando, Santa Clarita, and San Gabriel valleys, Las Vegas also mimics the pattern of Houston, Phoenix, and Scottsdale, Ariz., before it.

But there are social consequences to both additional numbers and the speed of growth. Robert Parker, an urbanist who teaches at the University of Nevada in Las Vegas, says the city has lacked viable planning and zoning laws as well as enforcement of those already on the books.

MISMATCHED segments make up the city. There are retirement villages like Sun City, and a so-called ``labor surplus/free trade zone'' north of town, which attracts homeless and other transients. Other separate areas include Nellis Air Force Base, an increasingly abandoned downtown, and the tourist-stuffed gambling strip. ``The city's different areas are not very well connected to each other,'' says Mr. Parker, who labels the phenomenon a ``multi-nucleated metropolis.'' He ticks off the list of problems that have come with both size and disjointedness.

First is the necessity of finding water to meet housing, business, and recreational needs (Article, below). Crime rates exacerbated by gang activity have pushed the city incarceration rate to three times the national average. The school district has grown into the nation's 11th largest. Result: some 18 schools now need to be built a year.

Because of heavy auto use and the same geology that inverts the air around Los Angeles, the number of unhealthy air days here hit 100 in 1994 - a 400 percent increase since 1993. ``Police, fire, trash collection, and social services are all more difficult to coordinate and are more expensive when you grow so helter-skelter,'' Parker says.

Still, interviews with families across the city indicate a high overall standard of living, one free from the sinister shadows many associate with gambling.

``People have this absurd notion that we all grew up in casinos,'' says Connie Brennan, mother of six and co-publisher of the Nevada Business Journal. ``They're surprised to find the people are really very conservative and wholesome. It's beautiful, open, and clean.''

To forestall one case of uneven growth, the city has a plan known as the ``Fremont St. Experience,'' a $60-million development that will place a canopy over several downtown casinos to tie them into a single entity alight with laser beams. Supporters hope the idea will stop the downward slide of downtown, where many casinos, failing to compete with glitzier gambling halls on the strip, have reported dwindling revenues.

There are also moves afoot to study the expansion of an existing downtown domed stadium, although Las Vegas has no professional baseball, hockey, or football team. Local officials envision a beltway encircling the city in the future and are studying the idea of a monorail to serve the gambling strip, whose boulevard cannot be widened because casinos extend to the curbs.