The median age is the age that divides the population into two equal-size groups. Half of the population is older than the median age and half is younger. Median age is based on a standard distribution of the population by single years of age and is shown to the nearest tenth of a year. (See the sections on "Standard Distributions" and "Medians" under "Derived Measures.")

The age dependency ratio is derived by dividing the combined under 18 years and 65 years and over populations by the 18-to-64 population and multiplying by 100.

The old-age dependency ratio is derived by dividing the population 65 years and over by the 18-to-64 population and multiplying by 100.

The child dependency ratio is derived by dividing the population under 18 years by the 18-to-64 population, and multiplying by 100.

Question/Concept History

The 1996-2002 American Community Survey question asked for month, day, and year of birth before age. Since 2003, the American Community Survey question asked for age, followed by month, day, and year of birth. In 2008, an additional instruction was provided with the age and date of birth question on the American Community Survey questionnaire to report babies as age 0 when the child was less than 1 year old. The addition of this instruction occurred after 2005 National Census Test results indicated increased accuracy of age reporting for babies less than one year old.

Limitation of the Data

Beginning in 2006, the population living in group quarters (GQ) was included in the American Community Survey population universe. Some types of group quarters have populations with age distributions that are very different from that of the household population. The inclusion of the GQ population could therefore have a noticeable impact on the age distribution for a given geographic area. This is particularly true for areas with a substantial GQ population. For example, in areas with large colleges and universities, the percent of individuals 18-24 would increase due to the inclusion of GQs in the American Community Survey universe.

Comparability

Caution should be taken when comparing population in age groups across time. The entire population continually ages into older age groups over time, and babies fill in the youngest age group. Therefore, the population of a certain age is made up of a completely different group of people in one time period than in another (e.g. one age group in 2000 versus same age group in 2019). Since populations occasionally experience booms/increases and busts/decreases in births, deaths, or migration (for example, the postwar Baby Boom from 1946-1964), one should not necessarily expect that the population in an age group in one year should be similar in size or proportion to the population in the same age group in a different period in time. For example, Baby Boomers were age 36 to 54 in Census 2000 while they were age 51 to 69 in the 2019 ACS. The age structure and distribution would therefore shift in those age groups to reflect the change in people occupying those agespecific groups over time.

Data users should also be aware of methodology differences that may exist between different data sources if they are comparing American Community Survey age data to data sources, such as Population Estimates or Decennial Census data. For example, the American Community Survey data are that of a respondent-based survey and subject to various quality measures, such as sampling and nonsampling error, response rates and item allocation error. This differs in design and methodology from other data sources, such as Population Estimates, which is not a survey and involves computational methodology to derive intercensal estimates of the population. While ACS estimates are controlled to Population Estimates for age at the nation, state and county levels of geography as part of the ACS weighting procedure, variation may exist in the age structure of a population at lower levels of geography when comparing different time periods or comparing across time due to the absence of controls below the county geography level. For more information on American Community Survey data accuracy and weighting procedures, please see https://www.census.gov/programs-surveys/acs/.

It should also be noted that although the American Community Survey (ACS) produces population, demographic and housing unit estimates, it is the Census Bureau's Population Estimates Program that produces and disseminates the official estimates of the population for the nation, states, counties, cities and towns, and estimates of housing units for states and counties.

Data on language spoken at home were derived from answers to questions 14a and 14b in the 2023 American Community Survey. These questions were asked only of persons 5 years of age and older. Instructions mailed with the American Community Survey questionnaire instructed respondents to mark "Yes" on Question 14a if they sometimes or always spoke a language other than English at home, and "No" if a language was spoken only at school - or if speaking was limited to a few expressions or slang. For Question 14b, respondents printed the name of the non-English language they spoke at home. If the person spoke more than one non-English language, they reported the language spoken most often. If the language spoken most frequently could not be determined, the respondent reported the language learned first.

Questions 14a and 14b referred to languages spoken at home in an effort to measure the current use of languages other than English. This category excluded respondents who spoke a language other than English exclusively outside of the home.

Write-in responses to Question 14b were categorized into more than 1300 detailed language codes. In 2019, American Community Survey language codes were standardized based on the International Statistical Organization ISO-639-3 standard. Using an automated computer system, the language coding procedure compared write-in responses with a master computer code list - which contained approximately 190,000 previously coded language names and variants - and then assigned a detailed language category to each write-in response. The computerized matching assured that identical alphabetic entries received the same code.
Clerical coding categorized any write-in responses that did not match the computer dictionary. When multiple languages other than English were specified, only the first was coded.

The write-in responses represented the names people used for languages they spoke. They may not have matched the names or categories used by linguists. Whenever possible, the write-ins were matched with an ISO-639-3 standardized individual language; however, language families and geographical terms were used if classifying at the individual language level was not possible. Presenting data for all languages is not sensible due to sample size and confidentiality concerns. The Four Group Classifications and Forty-Two Group Classifications of Languages Spoken at Home with Examples table in Appendix A provides an illustration of the content of the classification schemes used to present language data. These four-group and forty-two group classifications are used in many standardized data products previously disseminated on American Factfinder and now via https://data.census.gov beginning in 2023 data. However, many more languages are available in the American Community Survey Public Use Microdata Sample (PUMS) and in detailed tables packages. Languages as small as 10,000 speakers may be included in the PUMS dataset. For more information on the Public Use Microdata Sample, please see the PUMS technical documentation.

In households where one or more people spoke a language other than English, the household language assigned to all household members was the non- English language spoken by the first person with a non-English language. This assignment scheme ranked household members in the following order: householder, spouse, parent, sibling, child, grandchild, other relative, stepchild, unmarried partner, housemate or roommate, and other nonrelatives. Therefore, a person who spoke only English may have had a non-English household language assigned during tabulations by household language.

Government agencies use information on language spoken at home for their programs that serve the needs of the foreign-born and specifically those who have difficulty with English. Under the Voting Rights Act, language is needed to meet statutory requirements for making voting materials available in minority languages. The Census Bureau is directed, using data about language spoken at home and the ability to speak English, to identify minority groups that speak a language other than English and to assess their English-speaking ability. The U.S. Department of Education uses these data to prepare a report to Congress on the social and economic status of children served by different local school districts.

Government agencies use information on language spoken at home for their programs that serve the needs of the foreign-born and specifically those who have difficulty with English. Under the Voting Rights Act, language is needed to meet statutory requirements for making voting materials available in minority languages. The Census Bureau is directed, using data about language spoken at home and the ability to speak English, to identify minority groups that speak a language other than English and to assess their English-speaking ability. The U.S. Department of Education uses these data to prepare a report to Congress on the social and economic status of children served by different local school districts. State and local agencies concerned with aging develop health care and other services tailored to the language and cultural diversity of the elderly under the Older Americans Act.

Question/Concept History

The Language Spoken At Home Questions have changed only once since ACS began. Examples of languages were listed immediately followed the question “What is this language?” in the 1996-1998 questionnaire. Starting in 1999, the list of languages was moved to below the write-in box. In 2019, the code list for languages was standardized to match the International Statistical Organization’s standard ISO-639-3.

Limitation of the Data

Beginning in 2006, the population in group quarters (GQ) was included in the ACS. Some types of GQ populations may have language spoken at home distributions that are different from the household population. The inclusion of the GQ population could therefore have a noticeable impact on the language spoken at home distribution. This is particularly true for areas with a substantial GQ population.

The language question is about current use of a non-English language, not about ability to speak another language or the use of such a language in the past. People who speak a language other than English outside of the home are not reported as speaking a language other than English. Similarly, people whose mother tongue is a non-English language but who do not currently use the language at home do not report the language. Some people who speak a language other than English at home may have first learned that language in school. These people are expected to indicate speaking English "Very well."

Comparability

Caution should be taken when comparing language data from the ACS and 1980, 1990, and 2000 Censuses across time. Methodological changes to data collection in 2013 may have affected language data. Users should be aware of these changes when comparing data from 2013 or after to data from before 2013, or when using multi-year ACS data containing data from before and after 2013. For more information on comparability of language data, see the user note, "2013 Language Estimates."

The full Language Code List is found within the 2023 ACS Code List. Go to http://www.census.gov and enter "ACS Code Lists, Definitions, and Accuracy" in the search box