Hail Columbia! The federal government’s relentless expansion has made Washington, D.C., America’s real Second City.

The Washington, D.C., region has long been considered recession-proof, thanks to the remorseless expansion of the federal government in good times and bad. Yet it’s only now—as D.C. positively booms while most of the country remains in economic doldrums—that the scale of Washington’s prosperity is becoming clear. Over the past decade, the D.C. area has made stunning economic and demographic progress. Meanwhile, America’s current and former Second Cities, population-wise—Los Angeles and Chicago—are battered and fading in significance. Though Washington still isn’t their match in terms of population, it’s gaining on them in terms of economic power and national importance....