Why are some locations grey on the indicator detail page map?

On the indicator detail page map, sometimes a specific location is greyed out.

This could be for a couple of reasons: 

1. No data is available for that location: Sometimes we do not have data for every location for every indicator. The most common reason why we don't have data for a location is because the data was suppressed by the source, or by us, if there were only a very small number of instances. 
2. No data is available for that location for the selected comparison: If you are looking at multi-state site and select to compare to the state value, a distribution of state zip codes or state counties, locations outside of the selected state will appear greyed out. An example of this would be if your site covers counties in Indiana and Illinois and you select to compare zip codes to the Indiana state value. The map will only highlight with Indiana zip codes and display them as red or green. All the Illinois zip codes will be grey. If you switch the comparison to compare to the Illinois state value, all the Illinois zip codes will now be green or red and the Indiana ones will be grey.