The report is from the Violence Policy Center, a nonprofit that argues for gun control. You can read the study, which uses data from 2008, here. This isn't the first time that Missouri has been at the top of this list. From the AP:
There were 287 black homicide victims in Missouri that year, with 246 of those slayings either in St. Louis or Kansas City, according to statistics provided by the FBI. The result is a black homicide rate of 39.90 per 100,000 black residents, far higher than Pennsylvania’s rate of 31.05 per 100,000.
Nationwide, the overall homicide rate for 2008 was 4.93 per 100,000, according to the Violence Policy Center, which issued its annual black victimization report Wednesday.
I thought this quote from a KCPD deputy chief was interesting:
“The question I ask is, how as a police officer can I keep two people who know each other from arguing?” said Kevin Masters, deputy chief with the Kansas City Police Department. “When 81 percent of the violence is based on an argument, and 75 percent know each other, I don’t know that there’s a lot I can do."