Why the Rich Don't Give to Charity

"Around Washington, D.C., for instance, middle- and lower-income neighborhoods, such as Suitland and Capitol Heights in Prince George’s County, Maryland, gave proportionally more than the tony neighborhoods of Bethesda, Maryland, and McLean, Virginia."

I suspect that the proportion of church-goers is higher in Suitland and Capitol Heights, and among church-goers there is a larger proportion attending evangelical churches that drum in a message of tithing, or at least of heavy contribution.