Base Population - The population count or estimate used as the starting point in the estimates process. It can be the most recent updated Census count or the estimate for a previous date within the same vintage. The April 1, 2010 estimates base population may differ from the April 1, 2010 Census count due to legal boundary updates, other geographic program changes, and Count Question Resolution actions.
Births - Total number of live births occurring to residents of an area as estimated using reports from the National Center for Health Statistics (NCHS) and the Federal-State Cooperative for Population Estimates (FSCPE). The birth rate expresses births during a specified time period as a proportion of an area's population at the midpoint of the time period. Rates are expressed per 1,000 population.
Civilian Noninstitutionalized Population - All U.S. civilians not residing in institutional group quarters facilities such as correctional institutions, juvenile facilities, skilled nursing facilities, and other long-term care living arrangements.
Civilian Population - All U.S. residents not in the active-duty military.
Components of Population Change - Demographic events (births, deaths, domestic migration, and international migration) used to estimate changes in the population during a specified time period.
Deaths - Total number of deaths occurring to residents of an area as estimated using reports from NCHS and FSCPE. The death rate expresses deaths during a specified time period as a proportion of an area's population at the midpoint of the time period. Rates are expressed per 1,000 population.
Demographic Analysis - A technique used to develop an understanding of the age, sex, and racial composition of a population and how it has changed over time through the basic demographic processes of birth, death, and migration. Demographic Analysis (usually abbreviated as DA) also refers to a specific set of techniques for developing national population estimates by age, sex, and race from administrative records to be used to assess the quality of the decennial census.
FIPS Codes - Federal Information Processing Standards (FIPS) codes, issued by the National Institute of Standards and Technology (NIST), that identify each geographic area.
Group Quarters Population - All U.S. residents who live in group living facilities including correctional institutions, juvenile facilities, skilled nursing facilities, college residence halls, military barracks, group homes, and workers' dormitories.
Household Population - All U.S. residents who live in housing units such as single family homes, townhouses, apartments, and mobile homes.
Intercensal Estimates - Population estimates produced for the years between two decennial censuses when both the beginning and ending populations are known. They are produced once a decade by adjusting the existing time series of postcensal estimates for the entire decade to smooth the transition from one decennial census count to the next. They differ from the postcensal estimates that are released annually because they rely on a mathematical formula that redistributes the difference between the April 1 postcensal estimate and April 1 census count for the end of the decade across the estimates for that decade. For dates when both postcensal and intercensal estimates are available, intercensal estimates are preferred.
Median Age - The age which divides the population into two numerically equal groups; that is, half the people are younger than this age and half are older.
Natural Increase - Births minus deaths. The rate of natural increase expresses natural increase during a specified time period as a proportion of an area's population at the midpoint of the time period. Rates are expressed per 1,000 population.
Net Domestic Migration - The difference between domestic in-migration to an area and domestic out-migration from the same area during a specified time period. Domestic in- and out-migration consist of moves where both the origin and the destination are within the United States (excluding Puerto Rico). The net domestic migration rate expresses net domestic migration during a specified time period as a proportion of an area's population at the midpoint of the time period. Rates are expressed per 1,000 population.
Net International Migration - Any change of residence across the borders of the United States (50 states and District of Columbia). The estimates of net international migration are made up of four sub-components:
Net Migration - Net domestic migration plus net international migration. The net migration rate expresses net migration during a specified time period as a proportion of an area's population at the midpoint of the time period. Rates are expressed per 1,000 population.
Numeric Population Change - The difference between the population of an area at the beginning and end of a time period.
Percent Population Change - The difference between the population of an area at the beginning and end of a time period, expressed as a percentage of the beginning population.
Population Estimates - The calculated number of people living in an area as of a specified point in time, usually July 1st. The estimated population is calculated using a component of change model that incorporates information on natural increase (births, deaths) and net migration (net domestic migration, net international migration) that has occurred in an area since the latest decennial census.
Population Projections - Estimates of the population for future dates. They illustrate plausible courses of future population change based on assumptions about future births, deaths, net international migration, and net domestic migration. Projected numbers are typically based on an estimated population consistent with the most recent decennial census as enumerated, projected forward using a variant of the cohort-component method. For dates when both population estimates and projections are available, population estimates are the preferred data.
Postcensal Estimates - Population estimates produced for the years after a decennial census when only the beginning population is known. They are produced and revised each year. For dates when both postcensal and intercensal estimates are available, intercensal estimates are preferred.
Resident Population - All persons who are "usually resident" in a specified geographic area. The U.S. resident population includes all persons who usually reside in the 50 states and the District of Columbia, but excludes residents of the Commonwealth of Puerto Rico and the Island areas under U.S. sovereignty or jurisdiction (principally American Samoa, Guam, United States Virgin Islands, and the Commonwealth of the Northern Mariana Islands). In addition, the U.S. resident population excludes U.S. Armed Forces overseas and civilian U.S. citizens whose usual place of residence is outside the United States.
Resident Population plus Armed Forces Overseas - All U.S. residents and members of the Armed Forces on active duty stationed outside the United States. This population does not include military dependents or other U.S. citizens living abroad.
Residual - Population change that cannot be attributed to any specific demographic component of population change. This component results from one or both of two parts of the estimates process:
For specific definitions of the types of areas estimated and other geographic terms, please see Geographic Terms and Definitions.
For specific definitions of group quarters and housing units, please see Group Quarters and Housing Unit Estimates Terms and Definitions.