Variables, and the values they represent, may change over time. If you have used variables in prior year releases, check the ACS product changes webpage for source table changes. If the variable you have been using comes from a table that has changed from the prior year, check the variables list (variables.html) and compare the variable concept and label to be sure you are requesting the correct estimate. For information on these changes, visit:
The U.S. Census Bureau identified a problem with some variable labels within the 2016 1-Year ACS API endpoints. The variable label sometimes referenced 2015 instead of 2016. This resulted in some labels being incorrect.
The U.S. Census Bureau fixed this issue and variable labels are now correct. Data for these variables are correct and were not changed.
In September 2016, ACS released annotation variables that return character representations of each estimate. Many annotations return as null. However, if an annotation variable returns a value, it provides important information about the estimate or margin of error. For example, if an estimate variable (variable ending in “E”) returns “-888888888”, the annotation variable will return “(X)”. Looking at the Notes on ACS Estimate and Annotation Values, this means the estimate is not applicable or not available. For a complete list of return values and their annotations, see:
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