Real-estate experts in Mexico worry that the giant sound they hear is the softening U.S. housing market sucking out money Americans have poured into vacation homes south of the border.

But neither the cooling U.S. housing market nor tense Mexican presidential politics has stemmed the influx of foreign dollars into Mexico's booming coastal resort areas, government and real-estate officials said.

When Fonatur, Mexico's tourism-development agency, put the first phase of its newest Pacific Coast resort, Litibu, on the market a few months ago, buyers snapped up the 500 acres for $125 million. Foreign investment into Mexico is on track to hit $20 billion this year, up from $17.6 billion in 2005, the government says.

"We have some concerns about the slowing U.S. housing market, but there are many other things working for us," said John McCarthy, the tourism agency's director general, who was in Beverly Hills, Calif., last week to speak to U.S. investors. "Most of our buyers are baby boomers who have paid off in good part their initial mortgage and are coming into inheritance money."

Real-estate experts also said Mexico's resort-properties market might experience a smaller price shock because it is a new area of investment and the buyers tend to be higher-income and less likely to be forced into fire-sales.

"The cooling real-estate market could take this from being a very, very positive trend to a mildly positive trend," said Christopher Thornberg, an economist with Beacon Economics, a Los Angeles-based real-estate consulting company.

That's good news for Janette and Harvey Craig, who paid $60,000 four years ago for a piece of beachfront property in Litibu, a small beach community about 30 miles north of Puerto Vallerta.

The Craigs expect the parcel, worth about $300,000 today, to be more valuable in three years, when the nearby resort, which will include hotels and condominiums, 910 homes and an 18-hole golf course designed by Greg Norman, is completed.

"It's just going to push prices higher and higher," said Janette, a part-owner of Garcia Realty in the nearby surfing town of Sayulita.

In the past, foreigners have been wary of investing in Mexico because of legal problems, corruption and red tape. But changes in Mexican laws have made it easier for foreigners to own property through bank trusts. Major U.S. companies have begun offering mortgages and title insurance.

Mexico also is drawing more attention from Europe. Last year, Spanish companies were the top investors in the tourist industry, pumping $416 million into resort properties. U.S. investors followed with $321 million, according to the tourism agency.

McCarthy rejected the notion that tourism benefits only wealthy developers and well-heeled travelers. He pointed out that the average incomes in Quintana Roo and Baja California Sur, the states that are home to Cancún and Cabo San Lucas, are among the highest in the nation.

Tourism is the third largest generator of foreign exchange in Mexico, after oil and remittances from Mexicans living abroad.

Exclusive getaway

In just a few decades, the southern tip of the Baja Peninsula has become one of Mexico's most exclusive getaways.

Once known for cheap time-share properties, the rugged coast between Cabo San Lucas and the sleepier San José del Cabo is lined with luxury resorts that charge as much as $1,000 a night for hotel rooms. Oceanfront estates sell for as much as $7 million. On busy weekends, it is not uncommon to see 100 private jets at the airport.

Mexico's real-estate boom also has been helped by the development of upscale "fractional ownership" properties that allow people to buy a piece of a condominium or home.

Barry Hacker and his wife, Paivi, sold their beachfront home in Florida after it was damaged by two hurricanes in two years. They have invested, they said, "tens of millions" of dollars in a piece of waterfront property in Ixtapa, a West Coast resort area of Mexico. They plan to build a 10-room boutique hotel called Punta Romantica and offer fractional ownership in 10, four-bedroom villas on the property.

Hacker, a partner in KPMG's Tokyo office, said many wealthy Americans are selling their waterfront properties in Florida and California while prices are high.

"We can deliver a villa for a fraction of the cost that's also oceanfront and is fully staffed with all the hotel services, a gym, a spa and a restaurant," he said.

Mexican tourism officials are sensitive to criticism that this rapid development threatens some of the country's most beautiful coastline and marine reserves and puts a strain on the rural communities that bear the brunt of the rising land costs, increased traffic and an influx of people looking for work.

These challenges have come into sharp focus along the east coast of Baja California Sur, which borders the Sea of Cortez, home for the largest marine park in Mexico.

Fonatur has teamed up with Scottsdale, Ariz.-based developer Loreto Bay to build what is being billed as the "largest resort community in North America committed to the principles of sustainable development." The Mexican government invested $200 million on roads, water-treatment plants and other necessary services.

The $3 billion project, called the Villages of Loreto Bay, will create a town of 6,000 homes in neighborhoods designed for pedestrians and golf carts. No cars will be allowed. Nearly two-thirds of the 8,000 acres will be maintained as a "greenlands preserve."

Homes are being built from locally produced adobe brick, and the developer has leased land for a wind farm so the project can generate its own electricity, said Jim Grogan, Loreto Bay's president and chief executive officer.

Houses sell quickly

In two years, the project has sold 640 homes with prices starting at $380,000. Two-thirds of the buyers are Americans, many from California. Most of the rest are Canadians with a sprinkling of Mexicans.

"There's no question — people are willing to pay a premium for sustainable development," Grogan said.

The U.S. company has established a nonprofit foundation that has bought new equipment for the local hospital and a patrol boat for the marine conservancy, Grogan said. The Loreto Bay Foundation gets 1 percent of all home sales and resales, which totals $3 million so far.

Rob Faris, an economist with the Harvard Institute for International Development, praised the developer's efforts. But he worries about the effect such a large influx of people will have on southern Baja's limited water supply, the marine park and the community of Loreto.

Within two decades, the population of the sparsely populated region is expected to balloon from 15,000 to 120,000, according to a study co-authored by Faris.

"Their intentions are largely noble," Faris said of Loreto Bay. "But creating a sustainable community of this magnitude in Mexico — it hasn't been done before."