MACAU — The world's busiest casino town is straining to handle the affections of the world's largest population.

By the boatload, gamblers gripping Chinese passports jostle off ferries and cram, sardinelike, into a customs building in this once-sleepy former Portuguese colony on China's coast. They line up, hundreds deep on a weekend morning, for an entry stamp. Then they line up again for scarce taxis or catch shuttle buses into a town bristling with new casinos, fountains and resorts.

"I think it's become overwhelming," said David Green, a casino expert for accounting firm PricewaterhouseCoopers in Macau. "The infrastructure isn't really cut out to deal with that."

On a patch of land just one-sixth as large as Washington, D.C., Macau surpassed sprawling Las Vegas last year in gaming revenues, thanks to a growing deluge of mainland Chinese tourists. They are transforming this place faster than imperialism and organized crime ever did.

Indeed, the city that caused W.H. Auden in the 1930s to despair that "nothing serious can happen here" is being reborn as an economic tiger. Even compared to mainland China, with its skyrocketing growth of more than 10 percent per year, Macau stands out: Its economy grew last year by 30 percent.

"It's been crazy," said Paulo Azevedo, who has lived in Macau for 15 years and is publisher of the magazine Macau Business. "We used to have this sort of Mediterranean, laid-back quality of life," Azevedo added.

Macau comprises a peninsula and two islands located one hour's ferry ride from Hong Kong. For the last four centuries, Portugal ran the territory as a freewheeling bazaar and imperial outpost, trading silk, sandalwood, porcelain, opium, arms and other goods, all with a spirit of unabashed seediness. The colony was a "weed from Catholic Europe," as Auden put it.

The expansion of gaming in the 1960s didn't help. Macau became known for corruption and gangland violence, a demimonde inhabited by figures such as kingpin "Broken Tooth," finally locked up in 1999. By the 1990s, Macau's casinos, long a monopoly held by billionaire Stanley Ho, had slipped so far that the crown jewel, the Hotel Lisboa, struck one visitor as having "the ambience of a minimum-security prison."

Macau returned to Chinese control in 1999, as a semiautonomous region akin to Hong Kong. Beijing's handpicked leaders embarked on an overhaul, investing in infrastructure and opening the gaming industry to competition. The first foreign-owned casino opened in 2004: the Sands Macao, owned by Las Vegas tycoon Sheldon Adelson.

As luck would have it, an obscure immigration change gave the Sands a blessed start: In 2003, after the SARS virus dampened tourism, China experimented with allowing its citizens to visit Macau and Hong Kong without mandating that they be part of a tour group.

The Chinese flooded to Macau, the closest place to gamble from the mainland, where it is illegal. Chinese travel agents say the law doesn't let them peddle gambling-focused trips, so they finesse it.

"We never put 'visiting casinos' on the tour schedule," said Guo Yu, a marketing manager at China Comfort Travel in Beijing.

"Nor is a tour guide allowed to lead tourists to a casino, but if tourists personally want to go to casinos, we can do nothing about it."

Within a single year, the Sands Macao had paid for its own construction. By the end of last year, tourism had nearly quadrupled in a decade to 27 million people annually, according to figures released last week. More than half of them — and by far the fastest-growing segment — are from mainland China.

For a growing Chinese middle class still getting used to foreign travel, Macau packages can be had for less than $90 a night, including air fare from Beijing to Hong Kong.

On the immense, half-lit gaming floor at the Sands Macao, virtually all the customers are Chinese, speaking in dialects that mark them as being from China's north or south.

Most of them hunch around baccarat, roulette or dice tables. (Blackjack and poker aren't popular, and neither are slot machines.)

The drink of choice is tea or soy milk, because the gamblers prefer to stay sharp. Superstitions are common in this part of the world, so gaming rooms are designed to incorporate the lucky number 8 into styling and carpets, while the unlucky numbers 13, 14 and 4 (known to hasten assorted catastrophes) are avoided. Likewise, tables and dealers that acquire the dreaded taint of unluckiness can sit idle for hours.

In the lobby, posters announce upcoming attractions that wouldn't be out of place in Nevada: a reunion tour by The Police and a heavyweight prizefight between two paunchy has-beens.

Indeed, Macau is attracting visits by American boxing promoters intent on finding a Chinese outpost that might make up for the sport's ailing popularity in the U.S.

"I couldn't believe what I saw. It's unbelievable," promoter Arthur Pelullo of Philadelphia said of his first visit.

"They make the casinos in Vegas look small. ... There were people everywhere. It's like they were giving something away."

For local businesses in Macau, the boom is not trouble-free. Restaurants and shops face rapidly rising rents and a labor shortage.

The resident population numbers only half a million, and casinos can afford to pay the most.

Meanwhile, congestion on downtown sidewalks already threatens to lend Macau's charming plazas and colonial streets the grace of a shopping mall.

There are other signs of growing pains. A group of more than 100 mainland tourists sparked a riot last summer, claiming their guides were forcing them to spend too much on gambling and shopping.

The incident touched off a round of soul-searching in Macau about the impact of tourism on the region's character, though it did not exactly end with a decision to cool growth.

A vast new development on reclaimed land has been named the Cotai Strip and staked out with plans for at least 12 hotels that would more than double the city's total rooms.

"We're still in the beginning," said Azevedo, the publisher. "This is nothing yet."