I am ready to be proven wrong in my PREJUDICE, but ...
I presume:
Correlation between both party affiliation and pigmentation of the MAYORS in those cities would likely approach 90%.
Ready to be admonished.
Correction: incidence of a certain party affiliation AND a certain visible pigmentation are likely to HIGHLY correlate to being on this list, and HIGH on the list.
Had to fix my prior statement of prejudice.