These data come from the U.S. Census Bureau's American Community Survey. They are based on averages of data collected in 2017, 2018, 2019, 2021 and 2021. These estimates cannot be used to say what is going on in any particular year in the period, only what the average value is over the full period. The Census Bureau's data.census.gov also provides 1-year estimates for counties with at least 65,000 people. We use 5-year estimates because they are available for all counties and allow comparison to other counties within the region.
Educational attainment refers to the highest level of school completed. In Boundary between 2017-2021 . . .
NOTE: There is no problem with comparing these data to census data from 2000.