Better take it up with the Texas State Data Center--I found that map on their site:
http://txsdc.tamu.edu/maps/thematic/ You'll find the map in question among the first listed on that page, under the heading, "Population Distribution in the United States ("Nighttime") Maps"
In any case, it's no coincidence:
More lights, more people
More people, more liberals.
So?
In any case, it's no coincidence: More lights, more people
More people, more liberals.
Gee, by that logic, Africa should be awash with Conservatives.
-Jay