If you want evidence, then download the charts from the FBI’s UCR available every year at the fbi.gov website. One of the charts lists violent crimes by population of the area in which the crime is committed. Table 16 from the 2011 report contains this data:
City of over 1,000,000? 754.5 violent crimes per 100,000 inhabitants. Rural area (called “Nonmetropolitan counties”): 180.8 violent crimes per 100,000 inhabitants. That's fewer than 1/4 as many crimes in the rural areas (where guns are more prevalent) than in the urban areas (where guns are more regulated).
Stay away from the urban centers, and America is not a violent place.
You realize, of course, that the demographic that ends up sending the most representatives to Congress and the state houses is centered in and around these Major Metropolitan Areas.
But there is so much of America that is NOT in these metro areas. Remove the excess concentration of population from the urban area, and the stress that drives the insanity so prevalent in urban settings is vastly decreased.
All the evidence in the world, however, will still not convince people to abandon the cities and disperse. Cities are such marvelous machines for the concentration of wealth and power, that invariably, people are drawn there in hopes of getting some small slice of that money and power.
But alas, all the money is in a vault in the middle of the city in somebody else’s name, and all the power is vested in a small clique that is entrenched in City Hall.
Which leaves the vast preponderance of the people stressed and a little nuts.
Sometimes a lot nuts. And violent.