In St. Paul yesterday, a vote in the State Senate assured that Minnesota will become the 12th state in the Union to legalize same-sex marriage. As has happened in other states where SSM has been approved by legislative action, virtually all the Democrats voted in the affirmative, all the Republican in the negative.

We talk these days a lot about partisanship in Washington, but Washington is more a symptom than a cause of the country’s political divide. It’s out in the states, where partisan control is less subject to checks and balances, aka gridlock, that the divide is on clearest display. And the clearest case in point is SSM.

After Republicans gained control of both houses of the Minnesota state legislature in the 2010 Tea Party election, they put on the 2012 ballot  a constitutional amendment defining marriage as between one man and one woman. The amendment went down to defeat 53-47, as did the Republicans. By common consent, it was the defeat of the amendment that energized the majority Democrats to push the state all the way to SSM.

Over the past several decades, it’s been the cultural issues, not the economic ones, that have come to pit the two parties most starkly against each other. These issues may be less consequential by the usual measures of societal well-being, but for that very reason, they make it easier to draw partisan lines in the sand. That’s Culture Wars 101.