In the 30-odd years that Mike McMahon has shaped his life in southwest Houston, he has been transformed as often and profoundly as the community around him.

As a University of Houston football player in the 1970s, McMahon was one of the swinging singles drawn to the area's sea of freshly minted apartments. As a Gulfton businessman riding out the bust of the '80s, his first response to the growing immigrant presence was to call the Immigration and Naturalization Service and demand a roundup.

Finally, as a pragmatist and maybe even a hero, McMahon in the 1990s broke with white residents afraid of losing their neighborhood and co-founded the immigrant-based Gulfton Area Neighborhood Organization, or GANO.

As the Hispanic presence grew in the 1990s, white residents complained most about the day laborers who gathered on a street corner in hopes of attracting employers.

"More than crime, drugs, anything, it was just their presence there," McMahon recalls. "But today, if the immigrants see an Anglo walking around here, they say, `Oh, he must be lost.'

"That's change; that's big."

In the decade leading to the 2000 Census, whites in Gulfton, Alief, Aldine, Sharpstown, Fondren Southwest and other formerly upscale, homogenous and close-in enclaves didn't so much lose their neighborhoods; they left them.

Picture a stone dropped on the urban core and ripples of people spreading from within the Loop to the second-ring suburbs between the Loop and Beltway 8; and then beyond, to the outer-ring settlements and even unincorporated perimeter; Kingwood, The Woodlands, FM 1960.

Picture escalating flight to the suburbs and especially whites leaving growingly diverse neighbors; picture deepening segregation of whites from minorities and persistent divides by race, ethnicity and economic class.

Picture a much-touted multicultural mosaic that is actually filled with people who live in neighborhoods of people who mostly look like them.

This is the portrait painted by a University of Houston Center for Public Policy analysis of the 2000 Census conducted by demographers Karl Eschbach and Max Beauregard.

"Whites are leaving diversity," concludes Eschbach. "Classical white flight is still happening. This is not the 1950s we're talking about or the 1960s. This is the 1990s, and it's still happening."

Wherever minority populations most boomed during the past decade, the white population most declined.

Hispanics added at least 1,000 people in 203 of the 819 census tracts in the eight-county Consolidated Metropolitan Statistical Area. Blacks added at least 1,000 in 51 tracts.

But in three-quarters of these fastest-growing minority centers, the number of whites shrank. In two-thirds of the tracts that added at least 1,000 blacks, the number of whites dropped by at least 1,000.

Whites at a rapid clip fled the older second-ring communities where they once held sway but where minorities -- especially Hispanics -- now dominate.

Spring Branch, Alief, Sharpstown, Inwood, Aldine, Northside, Northline, Pasadena, Cloverleaf, Channelview and Galena Park all lost significant numbers of whites.

The 1990 Census snapshot of these once stoutly white areas suggested they were building diversity as whites, Hispanics, blacks and Asians moved in, says Eschbach. But during the decade, as minorities continued to flock there, whites moved out.

The last head count appears to have caught the neighborhoods in midtransition, as they tipped in the historical pattern from majority white to majority nonwhite.

"There was the boom, the bust, the transition, and it took awhile before people realized that their neighborhoods were shifting and changing," says Eschbach.

Between the Loop and Beltway 8, the white population dropped by 160,000, or nearly 30 percent, from 1990 to 2000. On the flip side, Hispanic numbers nearly doubled, swelling by 300,000, or 90 percent. The black population grew by more than 30,000, or 10 percent, as the Asian population increased by nearly 20,000, or 40 percent.

Whites were 45 percent of the population between the loops in 1990; in 2000, they were 28 percent.

Wherever there is a diversity party going on in Harris County and, for that matter, the rest of urban America, whites are leaving it.

In their wake and at their destination, the result is continued segregation and separation between whites and minorities.

According to a sociological index that measures degrees of segregation, the separation of whites from blacks in Harris County continues unabated; the separation of Anglos from Hispanics has greatly increased.

Except for the gentrifying neighborhoods inside the Loop like the Heights and Montrose, where white professional home buyers are gradually pricing minorities out of the neighborhoods, whites increasingly isolated themselves in mainly white pockets and abandoned mainly minority ones.

"Southwest Houston, especially, is getting the double whammy," says Beauregard, "an increase of minorities and loss of whites. That's why Sharpstown Mall is not the same place that it used to be in terms of $60 sweat shirts at Foley's. Not everybody can afford those."

McMahon's Gulfton, with its rows of down-at-the-heels apartments that still bear jaunty names from their swinging-singles days, makes an incongruous gateway for the newest waves of immigrants and their many children.

No matter.

The sprawling urban barrio was ground zero for the Hispanic population boom and by far the fastest-growing sector in the metropolitan area. But as Hispanics grew there by 81 percent, from 18,422 in 1990 to 33,424 in 2000; whites dropped 23 percent, from 6,371 to 4,908.

Efforts to achieve a better head count in 2000 may have had some impact, says McMahon. But in the teeming, 1,400-unit Napoleon Square, itself a cultural village, 60 percent occupancy rates just five years ago have skyrocketed to more than 95 percent. Other major apartment complexes are packed as well.

"There are people who think that the way to respond to this Hispanization is to call the INS," says UH immigration expert Nestor Rodriguez. "Mike was one of them.

"It's a transformation. But while one group is losing a community, another group is gaining. That's the story of human history: You win, and you lose."

In Spring Branch, where a mix of Latinos, Koreans and other groups also have changed the landscape, an ongoing study by the UH Center for Immigration Research documents similar white flight.

"But when I talk to Anglos there, what seems to be the big deal is not so much that they're ethnically or racially different but that they're not middle class," says Rodriguez. "They don't say they're not middle-class, but they say, well, look at them, they're out on the street corners looking for work; we're not used to that. But those are characteristics of working-class or lower working-class people.

"So the issue is: Are Anglos fleeing ethnic and racial differences or are they fleeing social-class differences? I would put my money on social class," Rodriguez says. "But then the big impact is when the two come together, racial and class differences. That can be overwhelming for some people."

In the once-resolutely white and Jewish Fondren Southwest, the population also grew at a fast pace during the decade. But there, as the now-dominant black population jumped by 60 percent, from 22,942 in 1990 to 36,625 in 2000, whites dropped nearly as precipitously, by 44 percent, from 23,994 to 13,328.

"It makes my kids uncomfortable," says Ruth Hurst, president of the Braeburn Valley Homeowners Association, who has reacted to the demographic shifts by plunging into community-improvement projects.

"You weigh the pros and cons. I don't have the money to move where I'd like to go, which is next door to Bob and Elyse Lanier," she says, referring to the former mayor and his wife, who live in a well-secured River Oaks high-rise. "I've dug in."

Beautification projects, preserving park space, beating back a planned chicken-processing plant, tutoring the minority children who live in the surrounding apartments -- all are part of Hurst's effort to accept the shifts she can't change and improve the ones she can.

Many of her original white neighbors are gone; the couple that lived next door for years has been replaced by a black one.

"It doesn't mean that the majority of the black, brown and Asian people who have moved don't have the same values that I do," says Hurst. "In my neighborhood we have a lot of blacks who have moved in, and nicer neighbors you won't find."

Hurst and, for that matter, McMahon may be exceptions.

The durability of local segregation documented by Eschbach and Beauregard is mirrored nationally in a report by University of Albany professor John Logan for the Civil Rights Project at Harvard.

At a time when Hispanics, in 2000, drew neck-and-neck with blacks as the nation's largest minority and, in Houston, overtook whites as the numerically largest group, urban whites drew ever farther from people of color, particularly Latinos.

The typical American white, according to Logan's report, today lives in a neighborhood that is 80 percent white, 8 percent Hispanic, 7 percent black and 4 percent Asian. The typical black lives in a neighborhood that is 51 percent black, 33 percent white, 12 percent Hispanic and 3 percent Asian.

Especially in cities like Houston, Dallas, Fort Worth and Austin, where Logan's segregation index recorded the sharpest increases occurred in Anglo/Hispanic separation, the average Hispanic lives in a census tract that is 40 percent to 50 percent Hispanic, 10 percentage points higher than in 1990.

"It's a disturbing trend," Logan says of the unprecedented levels of Hispanics living in dense Spanish-speaking and mainly detached urban islands.

Hispanics and other minorities of greater economic means are suburbanizing alongside whites, particularly in the modest portions of Fort Bend County that abut Fondren Southwest. But the 2000 head count may also have caught that county midtip, especially since whites racked up their largest growth in the most homogenous areas: Clear Lake City, League City, Kingwood, The Woodlands, FM 1960 and northwest Harris County, generally.

"In the good economic times of the '90s, essentially Anglos are taking the money and running to the suburbs, and they're running along with minority populations that also have the means to do so," says Eschbach, also a sociologist. "As new developments open up in Fort Bend, Montgomery and other outlying counties, if you've got the money, you're moving in. If you're black, brown, yellow or white, it doesn't matter."

But because whites, at the dawn of the millennium, still disproportionately "have the money," says Eschbach, the result still is segregation.

"In the 1990s, with good economic times, people could afford to resegregate," says Eschbach. "You may not even be very conscious about race. You're just thinking about where are the schools, where are the communities like what I want. And if you're an Anglo, a 100 percent Anglo neighborhood is probably your best choice -- to get the amenities that you want, to get everything.

"Why would you choose Missouri City if you're an Anglo moving in when here's Sugar Land, here's The Woodlands?"

But while affluent whites may leave or pass up the most low-end homes of the second-ring suburbs, for upwardly mobile minorities, these embody the American Dream.

Denver Harbor, Magnolia and other venerable east-side barrios long ago were mainly built out. The declining, historically black inner-city communities like Sunnyside, South Park and the Third, Fourth and Fifth wards also offer up little new and affordable housing.

But in Aldine, Alief, Pasadena, Spring Branch, Fondren Southwest and other second-ring suburbs, the residences left behind by whites and even some new construction allow working- and middle-class minorities to own their homes or upgrade a rental notch.

"They're looking for houses and nice apartments with landscaping and pools just like everybody else," says demographer Beauregard. "And security, everyone wants security.

"It's basic lifestyle things that people are looking for, and older urban neighborhoods don't always have that."

This is the bright side of the segregation measures. Anglos may live in enduring separation from minorities. But driven by the search for better and accessibly priced housing, those diverse groups increasingly live alongside each other.

In Harris County during the last decade, the integration of blacks and Hispanics increased by about as many percentage points as the separation between whites and Hispanics, according to the UH index.

"One of the key facts is that the minority populations, Asian, Latino and African-American, are all growing together," Eschbach says of the most diversifying areas. "The only group that's leaving are the whites.

"That's very important because there's been concern that African-Americans would become isolated from other minorities and that some of those groups would start to blend with whites.

"At least from this point of view, that's not happening."

Additional demographic data from the 2000 Census over the coming year will fill in details: Why the white exodus to the suburbs? What will come of the growing integration of minorities, particularly Hispanics and blacks? Previous studies consistently have found their relationship to be, at best, ambivalent.

"It's clear that the African-American community is very divided on issues of Hispanization and immigration," says UH's Rodriguez. "Almost any question we ask that is sensitive, like `Do immigrants take jobs away?' or `Is it OK to use Spanish in the U.S.?' we get about half who agree and half who disagree.

"What develops from this new residential coming-together is obviously what we're interested in. Do they form friendships, do they form neighborly cultures, or do they stay apart?

"Do they let the fences divide them?"