Petaluma's population grew by slightly more than 1 percent from 2011 to 2012, a larger growth rate than both the state and national averages and a clip that is outpacing other Sonoma County cities.
During that period, Petaluma's population went from 58,296 to 58,921 residents, according to U.S. Census Bureau's annual population estimates released last week.
Santa Rosa saw almost 0.8 percent growth, from 169,360 residents in 2011 to 170,685 in 2012. And the county's overall growth rate went from 488,082 residents two years ago to 491,829 last year, also a 0.8 percent growth rate.
The new data falls in line with what local economists have come to expect in Sonoma County, steady and moderate growth in the last two to three years.
That growth is owed to a number of factors, including steady job growth, a lower cost of doing business, lower housing prices and an unbeatable quality of life, said Ben Stone, executive director of the Sonoma County Economic Development Board.
"We're about the best value in the Bay Area in terms of housing availability and quality of life," said Stone, adding that Marin, San Francisco and San Jose did not see the same dramatic drop in housing prices that Sonoma County experienced.
Stone said the cost of doing business in Sonoma County is about 7 percent below the national average.
Marin County's population grew 0.2 percent between 2011 and 2012, from 255,493 to 256,069 residents. Though Napa County's total population grew almost 0.8 percent to 139,045 residents, the numerical increase was only 1,048 people.
Sonoma County's population grew by 3,764 people during that period and Santa Rosa's population grew by 2,607 people. The city of Sonoma's population grew by 1.2 percent to 10,849 residents, though that's only an increase of 128 people.
These population estimates comprise the nation's official population count between decennial censuses. They are based on administrative records such as county birth and death records. City populations are then derived by analyzing local population markers such as building permits.
Stone said he expected more steady growth in the local population if job growth continues to improve. In April, the unemployment rate in Sonoma County fell to 6.5 percent, the lowest level since 2008.
It was also the 11th straight month where the total number of jobs in Sonoma County was higher than in the previous month.
Population trends are often driven by the the net result of births vs. deaths. But other factors that drive growth include net migration in and out of the state and counties.
Christopher Thornberg, a founding partner with Los Angeles-based Beacon Economics, said state migration is driven in part by the relative unemployment rates between the states.
If California's unemployment rate is high compared to the rest of the United States, people tend to migrate out of the state. The opposite is true if the state's unemployment rate is lower relative to that of other states.
During the economic downturn of the early 1990s, people left the state, he said. When the economy improved in the late 1990s, they came back. With the more recent drop in housing prices, people again started coming into the state even during a bad economy, Thornberg said.
"Look what's happening in our housing market, the lack of supply means our housing prices are going up," he said.