E-2. California County Population Estimates and Components of Change by Year—July 1, 2000–2010

December 2011


Official State Estimates

This updated report presents revised state and county population estimates benchmarked to the 2000 and 2010 decennial census data. The statistical “error of closure” procedure corrects the estimation error in the original estimates. These estimates supersede those in the Department of Finance E-2 series for the 2000s published in December 2010.


The state and county populations are independently estimated using population change models benchmarked on official decennial census counts. The state population is estimated using the Driver License Address Change method. County population proportions are estimated using the average of three separately estimated sets of proportions. The final distribution of proportions is applied to the independently estimated state control.

State Estimate. The state population is estimated using the Driver License Address Change (DLAC) Method. This composite method separately estimates the population under age 18, 18 through 64, and 65 years and older. Administrative records such as births, deaths, driver license address changes, tax return data, Medicare and Medi-Cal enrollment, immigration reports, elementary school enrollments, and group quarters population are among the data used in this method. All data are in summary tables and do not reveal the identity of any individual.

County Estimates. County population proportions result from averaging three methods.

  • DLAC Method. A modified version of the state Driver License Address Change (DLAC) method is used for counties. County proportions of the state total result from changes in county population values for births, deaths, school enrollment, foreign and domestic migration, medical aid enrollments, and group quarters population.
  • Ratio-Correlation Method. This method models change in household population as a function of changes in the distributions of driver licenses, school enrollments, housing units, and deaths. Estimates of county group quarters are added.
  • Tax Return Method. County proportions are derived by the U.S. Census Bureau using matched federal income tax returns to estimate inter-county migration along with vital statistics, group quarters, and other information for the population aged 65 and over.

Data Considerations

Sources. Data used in estimation models come from administrative records of 17 state and federal departments and agencies. Timeliness and coverage in these series vary. Corrections, adjustments or
estimates may be made while preparing the estimates.
Accuracy. In general, estimates become less precise as the time from the last census increases.  Data and models used to produce population estimates are subject to both measurement and nonmeasurement errors.  This results in imperfect correlation between the data used to estimate the population and actual population change.  The data and estimating models have been thoroughly tested with decennial census results that provide benchmarks for the estimates series.  Data and methods are further refined and modified throughout the decade.

Suggested Citation

State of California, Department of Finance, California County Population Estimates and Components of Change by Year, July 1, 2000-2010. Sacramento, California, December 2011.