re: Technical Notes
Given surveys that I have seen showing that, all else being equal, lower income people tend to be more charitable as a percentage of their income, if you aren't including the standard deduction folks in analysis of charitable contributions, you probably are missing a lot of the picture.
Frankly, the "blue state/red state" thing is getting a bit old.
As I showed in other posts, the real picture is a lot more complicated.
This map, for example.