Fairfield County has become more diverse and experienced more growth than expected since 2000, according to the first figures released by the U.S. Census Bureau Wednesday.

While posting the slowest growth rate of the state's eight counties, Fairfield County's population increase of 3.9 percent was viewed as healthy by demographers.

And, bucking previous trends, it was led by gains posted in the county's largest cities, Bridgeport, Norwalk, Danbury and Stamford.

"If you look at Fairfield County, it's the cities that are growing," said Joe McGee, vice president of public policy for the Business Council of Fairfield County. "That shows tremendous confidence in the big cities. That's a big story -- Bridgeport, Stamford, Danbury they're all growing. Really positive news for the big cities."

Fairfield County gained 34,262 people, a little less than Hartford County's gain of 36,831 and New Haven County's gain of 38,469.

The percentage of residents who consider themselves white dropped or stayed about the same in nearly every community in Fairfield County, while huge gains were seen in the numbers of Asian and Hispanics, as well as the "other" category, which includes those of mixed racial heritage.

"We're getting more and more people who are multiracial," said Orlando Rodriguez, senior research fellow at Connecticut Voices for Children and a former Connecticut State Data Center manager.

That's one explanation for the decrease in white population in the state's four largest counties. More people reported being of more than one race rather than just white alone, he said.

While Hartford, New Haven, Fairfield and New London counties saw their white populations decline in real numbers, the remaining four counties saw the number of white people increase. However, every county in Connecticut showed more diversity than in 2000 as measured by the percentage of the population consisting of a single race.

Fairfield County's population is now 74 percent white compared to 79 percent in 2000. Litchfield is the only county where whites make up more than 90 percent of the population. In 2000, four counties in the state were 90 percent or more white.

Increased diversity was also evident in the cities.

In Shelton, for example, the white population stayed about the same, the black and Asian populations more than doubled, and the number of Hispanics grew by 77 percent.

The growth in Asian population and those claiming a race other than those tracked by the census, grew overall by more than 45 percent in the county.

What appears to be behind the growth? Jobs.

Jason Witty, Stamford branch manager of professional job placement and recruitment firm Robert Half International, said the numbers indicate there was a stable employment base to draw population to the county and state over the last decade.

"Post 9/11, a lot of companies moved north," he said.

That led to growth in Greenwich and Stamford.

He said the county saw an increased presence in the financial sector, with large employers like UBS and RBS opening facilities.

On top of that, major employers continued to provide stable employment anchors for the population, including General Electric Co., Xerox and Sikorsky Aircraft, as well as Praxair Inc. and Boehringer Ingelheim in the Danbury region.

"To really get a handle on this data, we're going to have to know whether the people moving into these cities are more affluent or less affluent," said Gian-Carl Casa, director of public policy for the state Office of Policy and Management. "In order to make judgments, we're really going to have to see more detailed data."

The U.S. Census will release more detailed data in the summer.