Colin Woodard has written a new book American Nations: A History of the Eleven Rival Regional Cultures of North America, in which he argues that America is really 11 separate nations. It is not a new idea; others have pointed out variously that we can be divided into 5 or 7 or 12 different regions, based on political outlook, ethnic balance, history, liberal/conservative balance and the like, but he makes a good case for his view.
Here is his map:
The point being that these regional grouping are so fundamentally different in outlook that contentions issues like gun control will never acquire a consensus.