People who stroll through Chinatown on Saturday nights bathe in the lights of intriguing new restaurants, hip tea shops, and stylish lounges.
But moving beneath that shiny exterior, as strong and powerful as an underground river, is a torrent of forces that threaten the neighborhood's very existence.
An influx of luxury housing, rising rents and land values, a soaring white population, and slipping Asian population could mean the end of Chinatown's 140-year role as a gateway for immigrants and a regional hub for culture and family.
That's the conclusion of a new study by a civil rights and education group that examined two decades of property and demographic records in the three big eastern Chinatowns - New York's, Boston's, and Philadelphia's.
"Chinatowns on the East Coast," the report said, "are on the verge of disappearing."
That does not mean the buildings will vanish, or that the neighborhoods will empty of people. Far from it. It means that, if unchecked, market factors promise to turn vibrant communities into "ethnic Disneylands" where visitors come to dine.
For at least a decade, people have watched Philadelphia Chinatown grow more gentrified. The former Clarion Suites at 1010 Race St. is now Ten Ten Condominiums, and a parking lot became the site of Pearl Condominiums, where units sell for $250,000.
What's new in the report by the Asian American Legal Defense and Education Fund (AALDEF) is the detail of the analysis - a block-by-block, lot-by-lot examination that reveals a level of change the report deems "staggering."
The study, "Chinatown: Then & Now, Gentrification and Displacement on the East Coast," relied on planning and urban-studies researchers at the University of Pennsylvania.
It showed that in Boston's Chinatown, Asians have become a minority. New York's Chinatown is saturated with hotels. In Philadelphia, the median price of a Chinatown home has nearly quadrupled in 20 years.
"The challenges that the report highlights are not new to me," said John Chin, executive director of the Philadelphia Chinatown Development Corp. "I believe that Chinatown's prospects are very good."
PCDC created affordable housing, including On Lok House for seniors. Now it is working to build Eastern Tower Community Center, to include 143 residences, 31 of them for moderate-income families.
When new housing comes onto the market, it tends to be expensive.
The old Metropolitan Hospital was converted to condominiums, and so was the former Hawthorn Suites hotel.
From 1990 to 2010, Chinatown's median house value grew from $69,800 to $262,700, the AALDEF study said. The citywide value was $142,800 in 2010. Between 2006 and 2010, the median rent in Chinatown was $931, compared to $683 citywide.
The study defined Chinatown as encompassing all the land north to Spring Garden Street and setting the western edge near 13th Street. That accounts for some growth figures. The report uses the commonly accepted southern boundary of Filbert Street and eastern boundary near Ninth Street.
Many people, of course, applaud new development, arguing that the market should rule in a capitalist economy. For young professionals, a Chinatown unit offers a short walk to workplaces, shopping, and restaurants in Center City.
"It's easy to blame a developer," said zoning lawyer Carl Primavera, who represents many city builders. "The bogeyman of developer gentrification pushing people out, I think that's a vestige of urban renewal back in the 1950s. . . . I don't think I would buy into the argument that our Chinatown has seen dramatic gentrification."
A new development that has drawn attention is Goldtex at 12th and Wood Streets, where penthouse apartments will cost nearly $6,000 a month.
"Gentrification has a negative connotation," said Michael Pestronk, chief executive of Post Brothers, the builder. "The definition of gentrify is to improve. . . . What's going on in Philadelphia Chinatown is not the kind of bad gentrification that happens in a lot of places."
The difference, he said, is local projects center on creating new structures or reviving empty buildings, not renovating existing housing so landlords can charge higher rents. Goldtex used to be a ladies shoe factory.
Ellen Somekawa, executive director of Asian Americans United, says she does not believe raising property values is always beneficial. "If you just make it about money and the marketplace, and who can pay the most for rent, that doesn't recognize or protect the unique role of a community like Chinatown," she says.
The people moving into the lofts and condos typically are not Asian.
From 1990 to 2010, the population of Chinatown and Chinatown North grew 143 percent, while the city population dropped 4 percent. The white population more than doubled between 2000 and 2010, while the share of Asian residents has fallen 3 percent since 1990.
Chinatowns historically served as destinations for thousands of poorer immigrants who relied on friends and family to find housing and jobs. But the neighborhoods' locations, often on the edges of downtowns, made them vulnerable.
In Philadelphia, residents have rallied to stop a prison, casino, and Phillies ballpark from being built in Chinatown. Pittsburgh's Chinatown was destroyed to make way for a highway. Chinatown in St. Louis was demolished to build Busch Memorial Stadium.
Chinatowns "have been destroyed by the state and state-led private development projects across many decades," said Domenic Vitiello, who teaches city planning at Penn and worked on the study. "Talking about gentrification in Chinatowns has to be a discussion cast in that larger frame."
Philadelphia Chinatown dates to 1870, when a man named Lee Fong started a laundry at 913 Race St. Then as now, immigrants may arrive unable to read a bus schedule or a want ad, and need the guidance of contacts in Chinatown.
Today, the report said, cultural history is exploited to attract the affluent.
"These lands are being seen as a desirable place to live," said Bethany Li, the AALDEF staff lawyer who wrote the study, "whereas before, they were seen as a place where you could dump things, such as stadiums and prisons."
Philadelphia's Chinatown could have disappeared in the 1970s, when the city sought to raze Holy Redeemer Chinese Church to route the Vine Street Expressway. The church survived, but the Gallery mall, Market East Station, and the Convention Center claimed chunks of land.
"At what point does Chinatown cease to be Chinatown?" the report asked. "The present rate of growth of luxury units will certainly overtake and gentrify these neighborhoods."