They were based on Census 2000 population counts, then manipulated to provide estimates for how populations have changed since then. Using 10-year-old base data is problematic, but it is the best available until Census 2010 counts are complete.
Population shifts in the Northern San Joaquin Valley have been particularly dramatic the past decade because of the region's building boom, followed by the foreclosure crisis and soaring unemployment.
Census Bureau estimates figure Modesto's population peaked in 2003 and has dropped about 1 percent since. It calculates Modesto had 202,747 on July 1, 2009, which was 1,709 fewer than it supposedly had in 2003.
The estimates take into consideration births, deaths, domestic and international migration, and housing unit statistics.
But some of the bureau's population numbers sound suspicious, considering how many homes have been vacated because of foreclosures. The estimates, for example, show Patterson, Los Banos and Stockton setting population records, despite the fact they have some of the nation's highest foreclosure rates.
Census 2010 should provide much more clarity.
The once-a-decade census is a door to door head count. Census takers this summer continue to track down occupants of homes that did not complete census questionnaires. Participation in the census is mandatory.
That 2010 data will start to be released this December. That's when state population counts, used to apportion seats in the U.S. House of Representatives, will be released.
By April 1, 2011, census counts for counties, cities and assorted other small geographic places will be released.
Bee staff writer J.N. Sbranti can be reached at firstname.lastname@example.org or 578-2196.