A few days ago, conservative radio commentator Rush Limbaugh crystallized, in his inimitable way, why a fight over immigration and a border wall has produced the longest government shutdown in history.

The political left, Mr. Limbaugh charged, has come to believe in “open borders.” More than that, he argued, this is just the latest radical notion on its way to becoming mainstream in American society: “How many of you ever thought gay marriage would actually happen in your lifetime?” Mr. Limbaugh said. “How many of you thought all the other crazy, corrupt, screwball social justice things would ever happen?…But there are a lot of things that a lot of people thought were never going to happen, and many of them have.”

As that suggests, the border-wall fight is more than a border-wall fight. It has crystallized a deep cultural divide, between those happy with the evolving face of America and those alarmed by it.

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The Wall Street Journal: The Wall Marks a Deep Cultural Divide