What is it?
Where a county's score falls compared to every other U.S. county on the same measure. A score in the 80th percentile means the county is worse than 80% of U.S. counties on that measure (when the measure is one where higher = worse).
Why it matters
Raw values like '8.3 µg/m³' don't tell you whether your county is unusual without national context. Percentile ranks make comparisons defensible because they explicitly anchor against the full distribution.
Data source
Banana Analytics methodology · View source →