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E-6. Population Estimates and Components of Change by County — July 1, 2010–2017

lifornia’s population grew 0.77 percent between July 1, 2016 and July 1, 2017 to total 39.6 million persons. This represents an increase of 301,000 residents during the last fiscal year. The current percentage increase continues the moderate growth that California has experienced for the past several years.

Natural increase (births minus deaths) remains the primary source of the state’s growth. The natural increase of 221,000 is comprised of approximately 486,000 births minus 265,000 deaths. The birth rate declined to 12.3 births per 1,000 population from 13.8 births per 1,000 population in 2010 and reached the fourth lowest level since the beginning of our data in 1905. As the baby boomer generation advances towards retirement ages, the death rate has slowly increased to 6.7 deaths per 1,000 population, up from 6.2 in 2010. Net migration added 80,000 residents. Net migration includes all legal and unauthorized foreign immigrants, residents who left the state to live abroad, and the balance of hundreds of thousands of people moving to and from California from within the United States. The state gained about 185,000 net foreign immigrants last year.

Since the national census on April 1, 2010, the state has grown by 2.4 million persons.

Methodology

The state and county population 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. Most of county populations estimates result from averaging the first three methods below. We use a Vital Statistics Method in 16 counties with 72,000 populations 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 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, 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 numerous 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.