FLINT, Michigan In a diner just down the road from the factory where he works, Art Reyes is talking about assembly line jobs and the robots that have taken them over.

He pauses to order a couple of the citys signature Coney dogs (hot dogs topped with chopped onion and a mixture of fine-ground beef hearts and spices). Coneys and the restaurants that still serve them are survivors of a more prosperous era, when Flint was known as a hub of industry and the automaker General Motors employed half the city.

Today, Flint is better known for violence , economic strife and an ongoing water crisis that exposed tens of thousands of residents to lead-tainted drinking water. Its a far cry from the citys heyday in the 1960s, when Flint was the epitome of the American dream and people flooded in for well-paid, secure manufacturing jobs. Even those without a college education could expect GM to provide them with what Reyes describes as a good, solid, middle-class life. Today, he notes, for the most part, those jobs no longer exist.

This job decline is true across the U.S., which saw nearly 6 million manufacturing jobs disappear from 2000 to 2010 about a third of the sectors total. Hardest hit were the Rust Belt states; Michigan alone lost 440,000 of these jobs .

Arguments abound in the Rust Belt as to where the manufacturing jobs went. Some support the narrative, spun loudly by Donald Trump, that free trade has allowed countries like China and Mexico to steal jobs; others blame unions.

Theres no easy explanation for what happened to places like Flint. But the influence of technology, particularly automation, is conspicuously absent from many debates taking place at the highest levels. Trump never mentions it when talking about reversing manufacturing job losses. His Treasury Secretary Steve Mnuchin, questioned last year about the threat of automation and artificial intelligence , said they were so far in the future that they were not even on my radar screen.

For Reyes, 50, a lifelong Flint-area resident who has worked at GM for 30 years, theres no question that automation played an outsize role in changing the city permanently. He has watched tens of thousands of manufacturing jobs leave. He has also watched with dismay the appearance of Make America great again hats on the heads of his colleagues, stunned that they would buy Trumps promise to bring back manufacturing jobs, which Reyes says are gone forever. While heavy industry still has a presence in the city, much of the work in factories like GMs Flint Assembly Pant, where he is an electrician, is done by robots.

A 2015 Ball State University study supports Reyes view . Led by economics professor Mike Hicks, researchers found that U.S. manufacturing is, in fact, enjoying healthy growth. The problem? It isnt benefiting human workers. Hicks and his co-authors found that productivity increases, largely driven by automation and technology, were responsible for almost 88 percent of manufacturing job losses in recent years. Machines allow factories to produce more with fewer people.

The upside, Hicks said, is that technology tends to create more jobs than it kills, and he thinks that will continue to be the case. But he cautions against confusing job creation with a return to old employment trends. The new job will come about, but it may take two or three years, it might not be in the same place, and it certainly isnt going to require the same set of skills, he said.

As researchers like Hicks sound the alarm about a coming wave of machines and AI likely to upend many medium- and low-skill jobs, Flint could serve as an indicator for challenges to come. That is, if America would only pay attention.