CHICLA 330: Gentrification In Latinx Comm. (Spring 2022) : Time & the Census
Time and the American Community Survey
The American Community Survey (ACS) is an ongoing statistical survey that samples a small percentage of the population every year. Different parts of the survey are always being surveyed, and new data products are released continually.
To complicate matters, different communities are surveyed over 1 or 5 years, or both, depending on the size of the community. (And from 2005 to 2013, there was a 3-year survey, for areas with populations of 20,000+.) This has implications for research, and comparing different data products. For more on the different surveys and estimates, see
- The Census Bureau's page When to use 1-year or 5-year estimates.
- "Understanding and Using ACS Single-Year and Multiyear Estimates," page 9 in the PDF document A Compass for Understanding and Using American Community Survey Data: What General Data Users Need to Know.
|Data set||Data collected over||Produced for areas with populations of|
|5-year||60 months||almost any size|
There will be time periods when more than one ACS data set is available for an area. For guidance on when to use which data set, see the Census Bureau's page When to use 1-year or 5-year estimates. It means striking a balance between currency and sample size/reliability/precision.
The 1-year estimates are NOT available for Census tracts, because Census tracts generally have a population of 1,600-4000 each.
2020 Decennial Census
The Decennial Census asked for information of all people in the U.S. as of April 1, 2020. As of February 2022, data from the 2020 Decennial Census is available mostly at the top levels of geography. The detailed files are still being tabulated. See the Important Dates page from the Census Bureau for updates on data availability from the 2020 Decennial Census. See the Important Dates page from the Census Bureau for updates on data availability from the 2020 Decennial Census.
Why It Matters
Time is important in (at least) two senses (pun intended) regarding the Census.
- It takes time to collect, compile, and publish Census data! Data from each survey are released over time, by geographic level, and states. This is the case for all Census surveys. The more detailed the data, the more people covered by a survey, the longer it takes to publish the data.
- Different surveys may reflect
- A given point in time: this is the case with the Decennial Census. Data is collected about the entire population as it was on one given day.
- An estimate of the characteristics of a given population over a period of time. The American Community Survey collects data over a one-year or five-year period. People are not surveyed multiple times in a given time period, but not all people in a given geographical entity are surveyed on the same exact date.