But as one factory in Wisconsin is showing, the forces driving automation can evolve — for reasons having to do with the condition of the American workforce. The robots were coming in not to replace humans, and not just as a way to modernize, but also because reliable humans had become so hard to find. It was part of a labor shortage spreading across America, one that economists said is stemming from so many things at once. A low unemployment rate. The retirement of baby boomers. A younger generation that doesn’t want factory jobs. And, more and more, a workforce in declining health: because of alcohol, because of despair and depression, because of a spike in the use of opioids and other drugs.

In earlier decades, companies would have responded to such a shortage by either giving up on expansion hopes or boosting wages until they filled their positions. But now, they had another option. Robots had become more affordable. No longer did machines require six-figure investments; they could be purchased for $30,000, or even leased at an hourly rate. As a result, a new generation of robots was winding up on the floors of small- and medium-size companies that had previously depended only on the workers who lived just beyond their doors. Companies now could pick between two versions of the American worker — humans and robots. And at Tenere Inc., where 132 jobs were unfilled on the week the robots arrived, the balance was beginning to shift.