The virtuous circle collapsed by the 1980s. Technological innovations changed factory work. (It’s incorrect to say that America doesn’t make anything anymore. U.S. manufacturing has grown steadily for the past several decades. Today’s factories, however, are filled with very few — albeit highly skilled — employees and lots and lots of machines.) The expansion of global trade meant that low-skilled American workers were competing with low-skilled workers abroad. And many of the country’s rules, like union-friendly laws and other protections for workers, were weakened or disappeared.

The forces that would eventually afflict the American middle class came early to Worcester. The development of the Interstate highway system, beginning in the 1950s, and containerized shipping a few years later, meant that factories much farther away could afford to ship to East Coast ports. Manufacturing became more consolidated — Heald Machine, for example, was bought by Cincinnati Milacron, which brought some of its workers (including my grandfather Stanley) to Ohio. There are still factories in Worcester — for example, Norton, one of Worcester’s biggest and oldest plants (which was bought by the French conglomerate Saint-Gobain in 1990). But long gone are the days when Worcester’s plants offered a decent job to just about anybody willing to put in a hard day’s work. New employees looking to join the middle class must have not just a high-school diploma but an associate degree, if not a bachelor’s degree.

For all its decline in the second half of the 20th century, Worcester did enjoy one bit of good fortune: In the 1960s, the University of Massachusetts placed its medical school in the city. The school, which continued to grow, brought several generations’ worth of high-paying medical jobs and a fair number of lower-paying support positions. Similarly, Worcester’s position close to the center of New England has been good for the transportation business. Many of my relatives who stayed in town have worked either in the medical center as nurses or in the transportation field as truck drivers, dispatchers, rail-yard inspectors. These are solid, stable jobs, but they don’t enable the kind of jump-up in socioeconomic status that my family experienced many decades ago.

If you drive around Worcester now, it’s easy to imagine there is no rising middle class, no aspiration at all. In reality, it’s just much harder to tell Worcester’s story simply. A century ago, you could have picked any three-decker and immediately grasped the basic life story of all its tenants: where in the world they came from, which factory they worked in, what their hopes and fears were for their children. Today things are not so clear. Deborah Martin, a professor of geography at Clark University in Worcester, has spent years leading students through the city and researching its social dynamics. She knows a fair bit: where the Ghanaians live, how the Latino immigrants are differentiated by country of origin. But she often finds herself noticing newly renovated three-deckers and wondering, who is that? What are they doing?

Worcester reflects what’s going on throughout the United States. There are a healthy number of higher-paying jobs. The Worcester area has a disproportionately large community of well-paid medical professionals, from nurses and midwives to physicians and microbiologists; it has a huge number of educators for its population, a result of having nearly a dozen colleges in one medium-size city. But it also has more than the average number of lower-skilled jobs at or near the minimum wage — food-service workers, personal-care aides and a host of other medical-care assistants.

John C. Brown is a professor of economics at Clark and a visiting scholar at the Federal Reserve Bank of Boston. He told me that Worcester is right in the middle when it comes to the current circumstances of once-flourishing manufacturing centers in New England. Brown says one quick way to assess a city’s fortunes over time is to look at its population. Many urban areas in Massachusetts experienced a population collapse in the 1970s and 1980s. But Worcester and some others have had slow and steady growth over the past few decades. Worcester, he notes, can’t credit its success to any one industry. It doesn’t have, say, Boston’s robotics or the tourism of Salem and Lowell. Worcester instead benefits from a whole bunch of things: hospitals, universities and a bit of manufacturing still. Nothing screams at recent immigrants or people struggling in other parts of New England to rush to Worcester to fulfill their dreams. The city’s economy is a more complicated tale.