There is a trend worth worrying about, which is the disappearance of manufacturing jobs from the workforce. Shortly after World War II, about one-quarter of employed Americans held manufacturing jobs. Now less than one-tenth do. From the perspective of individual businesses, this change is natural and desirable—rising productivity by definition means fewer people making more things. But it is troublesome for society as a whole, since factory jobs have historically buoyed the middle class and given rise to future industries and jobs, virtuous-cycle style.