(BTW: I find your claim that “the difference in the murder rates is
explained by the different racial fractions in each city” rather
strange, when Centerwall has shown that when household crowding is
controlled for, black and white domestic homicide rates in Atlanta are
the same.)

C. D. Tavares said:

Huh? ‘Scuse me, which one is Atlanta in: Seattle, or Vancouver?

The situation in Seattle may be different from Atlanta (and the black
and white homicide rates in Vancouver do not differ significantly),
but that is not the only piece of evidence that socio-economic status
explains racial differences in the rate of homicide.

Maybe I’m off the track here, but I believe the original claim was not
so much that the difference in murder rates could be explained by the
different racial fractions in each city (although, since you put this in
quotes I assume that’s what the original poster TYPED) but that the
increased murder rate for each of the racial fractions differed ONLY in
one fraction between the two cities, which difference entirely constituted
the difference in the rates for the two cities as a whole. In other
words, the rate for one specific fraction was relatively off the graph
and caused the entire discrepancy. Is this or is this not the case?

More or less. The difference is entirely associated with different
rates for minority groups (i.e homicide rate for whites was the same).
Of course this does not explain the difference. (Anyone who thinks
it does, must also accept that the different firearm homicide rates
also explains the difference, since the non-firearm homicide rates
were the same.)