No matter who wins Tuesday’s presidential election, now ought to be the time that policy makers in Washington come together to tackle America’s greatest economic problem: sclerotic growth. The recession ended more than seven years ago. Unemployment has returned to normal levels. Yet gross domestic product is rising at half its postwar average rate. Achieving better growth is possible, but it will require deep structural reforms.

The policy worthies have said for eight years: stimulus today, structural reform tomorrow. Now...