Method
Counts of population subgroups and total area population data are acquired from the U.S. Census Bureau’s American Community Survey (ACS). Data represent estimates for the 5 year period 2017-2021. Mapped data are summarized to 2021 census tract boundaries. Disability status is classified in the ACS according to yes/no responses to questions (17 – 19) about six types of disability concepts. For children under 5 years old, hearing and vision difficulty are used to determine disability status. For children between the ages of 5 and 14, disability status is determined from hearing, vision, cognitive, ambulatory, and self-care difficulties. For people aged 15 years and older, they are considered to have a disability if they have difficulty with any one of the six difficulty types. Indicator statistics are measured as a percentage of the total universe (non-institutionalized) population using the following formula:
Percentage = [Subgroup Population] / [Total Population] * 100
For more information on the data reported in the American Community Survey, please see the complete American Community Survey 2021 Subject Definitions.
Background
The American Community Survey (ACS) is a nationwide survey designed to provide communities with reliable and timely social, economic, housing, and demographic data every year. The ACS has an annual sample size of about 3.5 million addresses, with survey information collected nearly every day of the year. Data are pooled across a calendar year to produce estimates for that year. As a result, ACS estimates reflect data that have been collected over a period of time rather than for a single point in time as in the decennial census, which is conducted every 10 years and provides population counts as of April 1. The Census Bureau combines 5 consecutive years of ACS data to produce estimates for geographic areas with fewer than 65,000 residents. These 5-year estimates represent data collected over a period of 60 months. Because the ACS is based on a sample, rather than all housing units and people, ACS estimates have a degree of uncertainty associated with them, called sampling error. In general, the larger the sample, the smaller the level of sampling error. Data users should be careful in drawing conclusions about small differences between two ACS estimates because they may not be statistically different.
For more information about this source, including data collection methodology and definitions, refer to the American Community Survey data users website.
Note
Race and Ethnicity
Race and ethnicity (Hispanic origin) are collected as two separate categories in the American Community Survey (ACS) based on methods established by the U.S. Office of Management and Budget (OMB) in 1997. Indicator race and ethnicity statistics are generated from self-identified survey responses. Using the OMB standard, the available race categories in the ACS are: White, Black, American Indian/Alaskan Native, Asian, and Other. An ACS survey respondent may identify as one race alone, or may choose multiple races. Respondents selecting multiple categories are racially identified as “Two or More Races”. The minimum ethnicity categories are: Hispanic or Latino, and Not Hispanic or Latino. Respondents may only choose one ethnicity. All social and economic data are reported in the ACS public use files by race alone, ethnicity alone, and for the white non-Hispanic population.
Data Limitations
Beginning in 2006, the population in group quarters (GQ) was included in the ACS. Some types of GQ populations have age and sex distributions that are very different from the household population. The inclusion of the GQ population could therefore have a noticeable impact on demographic distribution. This is particularly true for areas with a substantial GQ population (like areas with military bases, colleges, or jails).