By claiming that it has the power to enforce its own immigration policy, even when that policy conflicts with federal law, Texas has reignited a debate about federalism that is as old as the United States itself. But with so many commentators invoking the past to justify their positions, it is crucial to get the history right.

Many cite the Civil War as an analogy to – and a cautionary tale for – the current moment. But the more accurate benchmark is not the war itself; it is the five decades of simmering constitutional conflict that preceded the war’s outbreak. The similarities between those years and today should be a warning to us all. Demands for states’ rights are what Thomas Jefferson described (in 1820) as a “fire bell in the night,” threatening to sound the “knell of the Union.”

On the eve of the Civil War, US President Abraham Lincoln proclaimed in his first inaugural address that “the Union of these States is perpetual.” But he might well have said, “Conflict about the structure of the Union is perpetual”: so it had been ever since the Constitution’s drafters laid down their pens in 1787.

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