This report provides population and housing data for California cities and counties from the 2010 Census to the 2020 Census and for each year in between. The intercensal estimate data have been adjusted to provide consistent growth patterns derived from actual changes that occurred between the 2010 and 2020 censuses using the Error of Closure (EOC) adjustment procedure.
Error of Closure Methodology
These revised intercensal estimates for 2010-2020 for the state, county, and city population and housing are produced by modifying previous estimates to account for differences between the Demographic Research Unit (DRU) test estimates on 4/1/2020 and enumerated census counts of the same day. The procedure to close these differences is called the “Error of Closure,” or EOC. The concept is to preserve the original growth patterns that transpire in the annual DRU estimates for population and housing but to realign the ten-year growth patterns with the bookend census data.
The EOC adjustment is applied after two consecutive censuses have been conducted; for this report, the two censuses are for 2010 and 2020. The EOC adjustment revises previously calculated intercensal estimates to mitigate the effects of estimation errors in a data series over the decade coupled with differential accuracy of two decennial censuses. For this report, the final adjustment was made after the 2020 Census data became available. This procedure statistically distributes the difference, called the error, between the 2020 Census counts and the DRU test estimate calculated as of the census date, April 1, 2020, to the previously calculated annual 2010 to 2020 estimates.
American Community Survey (ACS) data were used to distribute total 2020 census housing units into our standard housing types (single detached units, single attached units, two to four units, five plus or apartment units, and mobile homes). For the EOC report, to maintain historical consistency, housing unit types consist of single units (single detached and single attached units), multiple units (two to four and five plus units), and mobile home units. Accessory Dwelling Units (ADUs) have been recorded in the Annual Housing Unit Survey since 2018 but are included in the regular housing unit types as defined by the ACS. Due to difficulties in data collection surrounding the 2020 Census and the COVID-19 lockdowns, the Group Quarters (GQ) 2020 counts were adjusted. Jurisdictions that experienced large undercounts or overcounts of GQ populations were adjusted using administrative and survey data to better reflect the actual population residing at the location at the time of the census. In every jurisdiction where an adjustment was made to the GQ population there was an equal adjustment to the household population so that the total population still equaled the 2020 Census counts. The E-8 report will be updated with CQR corrections when they are reported and approved by the U.S. Census Bureau.
The E-8 report is the historical version of the annually produced E-5 population and housing reports with reduced detail for housing units by type.
Total population: sum of household population and group quarters.
Household population: number of persons living in occupied housing units.
Group quarters: non-household population such as nursing homes, school dormitories, state and federal prisons, and military barracks.
Total housing units: stock of all housing units, including year-round, vacant, seasonal or migratory units, and other vacant units.
Single units: family dwelling units include single family detached units (units which are detached from any other structure and have open space on all four sides) and single family attached dwellings (units which are attached to other units with adjoining walls extending from ground to roof that separate them from other adjoining structures and forms a property line). Each single family unit has its own heating system. Accessory Dwelling Units (ADUs) reside primarily in this category except where the jurisdiction indicates that the unit was built in a multi-family structure.
Multiple units: multiple family dwelling units include structures with two or more housing units.
Mobile homes: mobile homes used for residential housing.
(Note: Condominiums are considered an ownership classification, not a structural description, so they may be included in single or multiple types of units.)
Total occupied housing units: all housing units that are occupied. Equivalent to the number of households.
Vacant units: all housing units that are vacant.
Vacancy rate: the percent of vacant housing units for the area. The difference between total and occupied housing units divided by total housing units displayed as a percentage.
Persons per household: the average number of persons residing in occupied housing (household population divided by occupied housing units).
John Boyne prepared this report with subject matter expertise and technical contribution by Walter Schwarm. Jordan Bruhn assisted with review and data preparation.
State of California, Department of Finance, E-8 Historical Population and Housing Estimates for Cities, Counties, and the State, 2010-2020. Sacramento, California, November 2023.
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