Cities like Plano or El Paso have about 2 homicides per 100,000. Gun control cities like Chicago have about 20, and places like Detroit have over 50.
Chicken or egg? Wasn't gun control instituted in those cities at least partly
because there was already a high homicide rate? (Oops,
digits was making the same point at the same time.)
Also, you can't look at a small geographic area, such as a city, in isolation. If it has much stricter gun control than nearby jurisdictions, there are obviously going to be a lot of guns brought in from those jurisdictions.
If it's a chicken and an egg problem, the egg has hatched and is clucking around the yard.
There are many different reasons for gun control in some of the bigger northern cities. Some of it was from a culture clash where people from down South, who are extremely friendly but sometimes react to serious insults with lethal force, moved up north where people aren't as overtly friendly to strangers and like to hurl insults all day. The simplest solution was to disarm all the blacks. Other issues were inner city crime and gang activity, and the simplest solution was to disarm the blacks while pretending to disarm the Irish and Italians. It didn't really work out very well, because criminals have a much higher drive and incentive to get guns than their victims do, and of course they really don't care if they're breaking the law to do so.
Importing guns from outside the city is just a fact of life, and since the criminal gangs are fighting over control of cocaine and heroin distribution, drugs which have to come in from a hundred times as far and which are ten times easier for the police to detect along the entire route, the most effective conceivable attempts to stop gun smuggling will utterly fail. Heck, even ATF agents were selling military/police only pistols to Mexican drug gangs over the Internet.