In early 2008, moving from West Oakland to Antioch was a deal Felicia Duncan couldn't refuse.

"I had purchased a house, the kind of house I was able to get out there but I couldn't get here for the price," said the real estate agent and single mom. She moved into an almost-3,000-square-foot, four-year-old house that would have cost two or three times more in Oakland.

Today Duncan is renting out both her West Oakland and Antioch homes while living in an apartment in Oakland's Adam's Point section; she returned in early 2010 because Antioch didn't offer an adequate public or private education for her daughter, now a sophomore at Oakland's Bishop O'Dowd High School, and she couldn't hack the commute.

She's an exception, in that she came back. Many African Americans quit Bay Area cities for good in favor of lower housing prices, job opportunities, better schools or other draws elsewhere, according to data released Tuesday by the U.S. Census Bureau.

To some extent it's a statewide phenomenon. The 2010 census "Black or African American alone" category, including black people who don't identify as mixed-race but including those who also identify as Latino, now accounts for 6.2 percent of California's total population, down from 6.7 percent in 2000.

The change has been precipitous in the Bay Area's historically black cities: Oakland's and Richmond's black populations each dropped by 23 percent from 2000 to 2010. That means black people accounted for 35.7 percent of Oakland's population at the decade's start and 27.3 percent at its end; in Richmond, blacks went from being 36.1 percent to 25.9 percent of the city's population.

Elsewhere, Berkeley's black population decreased by 20 percent, San Francisco's by 19 percent, and East Palo Alto's by 31 percent.

Many people moved to the suburbs. Antioch, in Contra Costa County's eastern reaches, saw its black population double while nearby Brentwood's almost quintupled. Manteca's black population more than doubled, Tracy's by 91 percent, Stockton's by 30 percent. And further inland, Sacramento suburbs such as Carmichael, Elk Grove and Roseville saw significant black population increases.

The reason for the flight to the suburbs?

"From what I've observed over the past 10 years, I think it's redevelopment and violence," said the Rev. Andre Shumake, the Richmond Improvement Association's president.

Urban redevelopment has not met "the double bottom line" of providing good returns for investors while also benefiting the affected communities, he said. Redevelopment projects often displaced low- and moderate-income African-Americans and "many wind up not coming back, or they couldn't afford to come back taking their talents and skills elsewhere, and it leaves an incredible drain on the communities and the neighborhoods," he said.

"The gentrification and displacement is alive and well in Richmond," he said.

"As it relates to violence, I believe the devastation that many of these families have experienced and continue to experience meant families that could move away did move away to what they believed would be a safer environment."

Many times, he said, he has heard Richmond residents wish "if only I could just get out of here, take my family somewhere else."

Some have stayed and organized against crime, he said, while some "decided they were just going to pack up and leave."

Reggie Moore became Antioch's first African-American elected leader, a city councilman, in 2006. He said most of the black community's growth there seems to be in the city's newer southeast section -- an area in which he had advocated for slower, more limited development while serving as a city planning commissioner a decade ago.

Moore said most African-Americans probably moved to Antioch for the same reason he did in 1990, from Hayward. "You can buy a brand-new big home and triple your lot size for less than say a 60-year-old house in Oakland. The weather is warmer, there's just a lot of opportunity," Moore said.

Some might have brought their urban attitudes with them, Moore said, and the city has felt some culture shock. Moore said he has witnessed some racial insensitivity, which surprises him given the overall Bay Area's progressive nature.

"There are times I've been taken aback, even shocked," he said.

A Cal State University academic saw a very old trend in the population shift.

This week's data reveals market forces that have been shaping America's cities for 150 years, perhaps exacerbated by the now-burst housing bubble, said Benjamin Bowser, emeritus professor and former chairman of the Sociology and Social Service Department at California State University, East Bay.

"African-American communities have generally been at the bottom of the housing pool in terms of price, cost and generational inheritance," he said. "After other groups have settled communities and moved on, African-Americans have found that's where they can buy into."

Property values in historically black neighborhoods of Oakland, Richmond and other cities dipped to a point where they looked like bargains to more affluent people hoping to live near major urban centers. Many blacks suddenly saw their housing values rise, even if most of the rest of their economic outlook had not improved.

"And all of a sudden someone wants to give them obscene amounts of money for their property. That results in people selling and then taking that money and buying into newer, roomier, 'better' properties in their interpretation away from the Bay," Bowser said. "These are going to be the new black communities for the next couple of decades, and the old black communities will be transitioned into new uses."

This is producing a model more like European cities such as London and Paris, he said, in which poorer people of all ethnicities live in a ring around the urban center, commuting in to work. Better enforcement of ordinances that require new urban housing development to include space for low- and moderate-income households could ease this, he said, but ultimately "if values go up and you're sitting on that, you get moved, and you get moved to places where values have gone down. That's the nature of the market and of the economy."

Another expert generally agreed with one reason for minorities moving to the suburbs, but cautioned that the housing crisis might be affecting the data.

With Oakland and other local cities hit hard by a foreclosure crisis that occurred during the census count, "that means the population of the community is in flux at that time" and so becomes harder to accurately count, said Steve Spiker, research director for the Oakland-based Urban Strategies Council.

For example, people who have lost their homes and moved in temporarily with relatives or friends might not be fully accounted for, he said.

"There's a lot of big social churning that's happening right around the census time so it's hard to intricately trust the data."

Staff Writers Paul Burgarino and Lisa Vorderbrueggen contributed to this report. Read the Political Blotter at IBAbuzz.com/politics. Follow Josh Richman at Twitter.com/josh_richman.