The UK does not have quite the racial divide that is prevalent in the US. Remember that minorities were treated as second-class citizens here as recently as the 1960s, and are still subject to institutionalized discrimination. Socioeconomic mobility is much worse here than in the UK, reinforcing the "ghettoization" of minority groups in the US.

Factor in easy access to modern weaponry, an actively-discriminating and mostly white police force, and the war on drugs, and you have a mixing pot of racial tension, poverty, and crime.

Oregon is mostly white, so is Minnesota, Vermont, and New Hampshire. A city like New Orleans is 67% black, is mostly poor, and has one of the highest homicide rates in the country. I haven't come across a city like that in the UK.

My home town, Portland, is extremely segregated. The black population here is concentrated in an area smaller than a square mile in the Northeast quarter, and both crime rates and gang activity there outrank the rest of the city by a factor of five. This is a consequence of Oregon's racist policies (our state constitution actually banned African-American residency) that were in force until World War II, when a large black population migrated here to work at a shipbuilding yard in Northeast. After the war, a flood took out the shipbuilding yard and put most of those families out of work; their descendants are still in the same area, subject to socioeconomic pressures that keep them there.

So while Portland might sound like a great place to live, it is only because the crime is segregated into a small section of the city while white people enjoy kitchy neighborhoods and craft fairs.