Where does the data come from and how current is it?
The data are the most current data from the US Census Bureau for Census block groups which is from the American Community Survey's 2021 5 year estimates. Block groups are a small Census geography that are generally defined to contain between 600 and 3,000 people.
American Community Survey
The US Census Bureau has taken American Community Survey data collected in 2017, 2018, 2019, 2020 and 2021 and uses this data to produce demographic estimates for block groups for 2021. When the Census Bureau collects income data in 2017 and then uses that 2017 data to estimate the 2021 income, they adjust the income reported in 2017 to 2021 dollars to account for inflation.
Most folks are familiar with the US Census Bureau's Decennial Census (2010 & 2020) that sends a survey out to all (ideally!) US households. But what's not as well known is that the US Census Bureau also collects data each year from a much smaller sample of US households. They use this annual data to produce a dataset called the American Community Survey.
The American Community Survey (or the ACS) is the ongoing, annual survey of the social, economic, housing, and demographic characteristics of the nation’s population. It is a survey of 3.5 million addresses and informs over $675 billion of Federal government spending each year. This dataset is released in 3 parts each year:
- 1 year Estimates for geographies with a total population of 65,000 or more
- 1 year Supplemental Estimates for geographies with a total population of 20,000 - 64,999
- 5 year Estimates for geographies with a total population of less than 20,000
A Short History of the American Community Survey
- 1790 - The first census was conducted and occurred every 10 years using one form to collect data.
- 1940 - The decennial census began using a short form for all households and a long form for a sample of households.
- 1990's - The long form data was recognized as becoming less and less current as the decade went on.
- 2005 - The ACS was implemented to collect data for all of America's communities each year.
ACS Data vs. Census Data
Where to Find Citations
You can find the full citations at the bottom of all the radius report website pages in the section called "What is the source of the demographic and population radius data above?".