The regional difference goes all the way back to English colonization of the American continent. Different colonies came with different folkways and attitudes around things like violence. An illustration: the colonists to New England, brought stick-and-ball games, the ones to Virginia brought bloodsports like the ‘gander pull’ (trying to yank a gander’s head off as you rode by on horseback).

If you’re interested, David Hackett Fisher catalogs what seem to be all the inter colonial differences in Albion’s Seed.

Colin Woodard (who’s here on Medium) picks up the thread in American Nations, and then picks up one of the ongoing conflicts (liberty vs common good) and how that plays out between the different ‘nations’ that are either descended from those colonies, or from Mexico, or otherwise happened.

You don’t need Fisher’s book to understand Woodard’s (and to be fair, Albion is something of an encyclopedic slog — but also worth it).