Birmingham, St. Louis & Memphis have the highest levels of gun violence, though? Not sure if those are the most "progressive" places.
Also Mississippi (more than 10x worse than e.g. Massachusetts), Louisiana, Alabama are the top 3 states by gun homicide rate.
If Mississippi was a country it would be in the top 10 (between Mexico and Columbia) by gun related murder rate which is quite an achievement..
Massachusetts
As for the specific cities you mentioned, policies enacted by local governments over decades generally fall into the progressive category. State and federal governments certainly share some blame for the problem but because the causes are mostly local any solutions will also have to be local.
We can all agree that taking away peoples' guns would lead to less gun violence. (This is the part where you say "but that's impossible anyway" or "but the 2nd amendment" which doesn't really refute my point)
Yeah schools are pretty local.
Not sure what is progressive about the fact that one can easily obtain a gun. Pool with many legal guns makes it easier to obtain it illegal one as well.
There would be even less violence in Mexico if they were not bordering USA.