E-TE: Census 2010 and Population Test Estimates for Cities, Counties, and the State — March 31, 2020

October 2020


These population estimates are produced once a decade by the Department of Finance to provide the best estimate of population and housing as of March 31, 2020 for the state, counties, and incorporated municipalities. The 10-year perspective allows for retrospective consideration of the trends and changes that have occurred over the decade. Additionally, these estimates provide for evaluation and invite comparison to the Census 2020 results which will be released by the Census Bureau beginning in spring of 2021.

These estimates are strictly for informational and research use only. They are not to be used by local areas to calculate their annual appropriations limit. Likewise, this March 31, 2020, estimate should not be used for budget or programmatic applications.


City and Unincorporated Area Estimates. The Housing Unit Method (HUM) is used to estimate total and occupied housing units, household size, household population, and group quarters population. American Community Survey (ACS) data were used to distribute 2010 census housing units into Department of Finance standard housing types (single detached units; single attached units; two to four units in structure; five plus, or apartment units; and mobile homes). Housing units are estimated by adding new construction and annexations then subtracting demolitions, followed by an adjustment for units lost or gained by conversions. Annual housing unit change data are supplied by local jurisdictions and the U.S. Census Bureau. Occupied housing units are estimated by applying a derived civilian vacancy rate to the estimated civilian housing units. Vacancy rates are based on 2010 Census benchmark data, adjusted to incorporate the directional changes described by the latest available ACS data. Exact data on foreclosures or other housing market indicators are not reliably available to adjust vacancy rates and are not used.

Military occupied housing units are added to civilian occupied housing units to calculate total occupied housing units. A survey of military facilities is used to track military changes including base realignments and closures.

Household population estimates are derived by multiplying the number of occupied housing units by the current persons per household. The persons per household estimates are based on 2010 census benchmark data and are adjusted by raking the current county population series into these estimates. The group quarters population is based on the Census Bureau’s 2010 SF1 File counts on group quarters and annually adjusted using reported changes for group quarters by state, federal, and local agencies. The household and group quarters populations are summed to produce the initial city population estimates. These estimates are aligned to the county estimates described below.

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 used to develop these estimates are in summary tables and do not reveal the identity of any individual.

County Estimates. Most of county populations estimates result from averaging the first three methods below. We use a Vital Statistics Method in nine counties (Alpine, Calaveras, Inyo, Mariposa, Modoc, Sierra, Siskiyou, Trinity, and Tuolumne) with populations 65,000 or less.

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 care and medical aid enrollments, and group quarters population.

Ratio-Correlation Method. This method models changes in household population as a function of changes in the distributions of births, driver licenses, school enrollments, labor force, and housing units. 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.

Vital Statistics Method. County population estimates result from changes in county population values for births, deaths, and group quarters population.

Data Considerations

Sources. Data used in estimation models come from administrative records of several state and federal government departments and agencies, and from the local jurisdictions for which Finance produces population estimates. Because timeliness and coverage in these series vary, corrections, smoothing, and other adjustments may be applied. Changes to 2010 Summary File 1 data in the classification of student housing on or near campus was necessary to remain consistent with the census group quarters definition. In only a few instances, some student housing (residence hall and apartment units) counted as household population in the census was redefined as group quarters student housing population. College dorm group quarters population is defined as student population living in residence halls and apartment units located on or near college campuses.

Suggested Citation

State of California, Department of Finance, Report E-TE:  Census 2010 and Population Test Estimates for Cities, Counties, and the State — March 31, 2020. Sacramento, California October 2020.

Contact Information

For questions on the population test estimates, please e-mail at ficalpop@dof.ca.gov or call the Demographic Research Unit at 916-323-4086.