Think about what changing the categories might create...yeah, exactly, possibly some fewer swing states, nothing else. I fail to see how fiddling that way creates a more polarized picture.
Equal intervals don't actually make much sense in creating a meaningful map. Percentiles are much better. Natural breaks are even better. Not that I know whether his map obeyed any of these.
And I'd like to know what the maximum is. Maybe he should have used a few shades more.
But, yes, of course, this map is trying to make a cheap political point, ie how similar this map is to the current political alignment in the US, and is leaving out such subtleties.
The problem is the highest and lowest values; why 1-3 for the first?
That's dodgy as hell. I suspect the higher limit plays a similer trick, but I don't especially want to wade through statistics on lynchings.
I'm *not* denying that most lynchings happend in the South, what sort of idiot would deny that, what I hate about that map is the distortions to make it "fit" with the states that voted for Bush.
O/c this can be played both ways, I bet if you got the stats by county, it would show more lynchings in counties lost by Bush than won by him (most lynchings happend in the Black Belt IIRC). And it would be just as intellectually dishonest.