The state and the PD has far more influence over access to firearms and serious crime than a city's politics do. A city's authority is largely limited to handing out parking tickets and graffiti citations.
And republican supermajority states have never had any issue overriding any municipal legislature or policies that they don't like. It's as easy as drafting a piece of legislature for them. Municipalities don't enjoy even the illusion of sovereignty, or, really, any codified rights in the US.
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And if you think it's the cities; fault, why is the homicide rate outside of cities in deep-Republican states so high? Missouri, Alabama, Mississippi, Arkansas, Alabama, Georgia, Louisiana, the Carolinas... All have a horrible state-wide violent crime problem. How many more decades of Republican supermajorities will they need to bury the myth that Republican policies reduce crime?