Louisville? Not even close. Try East St Louis for the worst of America and parts of New Orleans
St. Louis is one of the few bigger midwestern/eastern cities I've not lived in. But I have spent time in all the others mentioned, inluding long times in Lousiville and Memphis, and in the time I was in Lousiville it was terrible the amount of crime and violence I saw, on top of the entire city effectively being under construction since 1975 or so.
However, I looked it up once I got off work and you are correct in terms of violent crimes (in the study I found, homicides.) Of the 50 most violent cities in the world they all belong to either Africa, South America, or the United States, and 41 belong to Latin America. The U.S. has 4 in the top fifty, New Orleans, Detroit, Baltimore, and St. Louis, with St. Louis being the highest at #15 with almost 60 homicides per 100,000 people. These numbers were also published just 5 days ago, so it's as new as you can get.
But, sadly, the difference in the top 5 and the rest is astronomical. The 5 cities are Maturin, Venezuela with 87 homicides/100k, then it jumps enormously to Aculpulco, Mexico at 105/100k, San Salvador at 108/100k, San Pedro Sula, Honduras, at 111/100k, and #1 is Caracas, Venezuala at an insane 120/100k.
So yeah, as bad as the worst city in modern western culture is, the worst in South america is literally twice as bad when it comes to homicide.
But I will also just post the disclaimer from said article as well for the criteria of the cities
The council's ranking contains cities with populations of more than 300,000 and does not count deaths in combat zones or cities with unavailable data, so some dangerous cities may not be represented on the list.
So, it is possible that some middle east cities do have it worse because they are technically combat zones, but I wasn't able to find numbers for any of those.