It would be understandable for denizens of Nashville, Houston, or Miami to be indifferent to the current fate of America’s troubled “blue cities.” New York, Chicago, San Francisco, and Detroit, for example, have become notorious for a toxic combination of street homelessness and crime, on top of pandemic population loss. All are governed by Democratic mayors and populated by Democratic majorities. The fact that these social ills can be linked directly to poor local governance, including bail “reform laws” that spring criminals, makes it even harder to feel these big cities’ pain. But indifference is far from the best response. In the vast, interconnected free trade zone known as the United States, a decline of what had been robust, job-producing cities affects the nation as a whole. And we all will, literally, pay the price....