In many ways, Detroit, Michigan is the perfect place for Donald Trump to try to appeal to the American people. It is a once-great city that badly needs to be made great again. It's a place where today, nearly 40 percent of residents live in poverty and per capita income is roughly $15,000—about half the national average. For Trump, it's a fitting venue to make the case that the United States' economic outlook is "really bad!" "Sad!" And, lest we forget, "a total disaster!"

Trump did as much when he addressed the people of Detroit Monday morning at the Detroit Economic Club, where he spouted off grim statistic after grim statistic about the city, which, he said, "was once the economic envy of the world.”

Even the legions of online fact-checkers, both professional and amateur, who scour Trump's transcripts for inaccuracies couldn't argue with those figures. But while Trump may have been right about Detroit's many ills, he hasn’t quite accurately diagnosed the cause.

Detroit as a city was killed in part by itself. Harvard's John Macomber

As Trump sees it, Detroit's main issue is trade deals like the North American Free Trade Agreement, which was signed during Bill Clinton's presidency, and which Trump says sent precious automotive industry jobs overseas. "Detroit is still waiting for Hillary Clinton’s apology," Trump said Monday, before sneaking in a dig. "I expect Detroit will get that apology right around the same time Hillary Clinton turns over the 33,000 emails she deleted."

But experts say blaming trade is at worst wrong, and at best a vast oversimplification of the case. Blame the unions. Blame Detroit’s dependence on a single industry. Heck, blame the robots. But, they say, don't blame trade, or at least, do so at the risk of jeopardizing even more industries across the country.

"Free trade has enabled US agriculture, aerospace, IT, fashion, entertainment, pharmaceuticals, and of course hotels to thrive," says John Macomber, a senior finance lecturer at Harvard Business School.

The first and most glaring issue with Trump's argument is his insistence that all of Detroit’s automotive jobs now exist somewhere overseas. Some do. But many don't. In fact, many of them have just moved to southern states. And that’s not a new phenomenon, either.

Since the 1950s, American automakers have been relocating factories outside of Detroit to states like Kentucky and Mississippi where union presence isn’t as strong. Foreign car manufacturers have been going into those states, too. What that means is that while Detroit may be suffering from job loss, other cities like Jackson, Mississippi and Nashville, Tennessee are exploding with high-tech auto industry jobs.

“Free trade did not kill the auto industry. The industry is robust today,” says Macomber. It’s just not concentrated in Detroit.

It also requires a lot fewer people, explains Chad Moutray, chief economist of the National Association of Manufacturers, which has spoken out against Trump’s trade policies in the past. Moutray says he bristles at the idea that manufacturing in the US is dead. “We make more in America today than we ever have,” he says.

The difference is that even as productivity has grown, automation has shrunk employment in that sector. "The sector has changed pretty dramatically," Moutray says. "It requires a different type of worker than it used to." Those workers are now highly trained technologists, doing skilled labor rather than the type of assembly line work that once kept the citizens of Detroit afloat. Ending global trade deals will not revert the industry back to pre-automated days. The robots, so to speak, are out of the bag.

Of course, Trump isn't the only one talking tough on trade this election cycle. During primary season, Senator Bernie Sanders trumpeted his history of voting against NAFTA and came out against the newly signed Trans Pacific Partnership, or TPP. His approach to trade, many argue, forced Democratic nominee Hillary Clinton to scale back her support for free trade. Though Clinton originally called the TPP "the gold standard," she says she has since changed her mind. During her speech at the Democratic National Convention, she said anyone who believes "we should say 'no' to unfair trade deals" should support her candidacy.

At the same time, however, Clinton has also unveiled an aggressive technology and innovation agenda, that not only reads like a Silicon Valley wish list, but also aims to prepare workers displaced by changing industries for the jobs of the future. Clinton will also travel to Michigan this week to lay out her vision for the economy.

None of this is to say that free trade hasn’t made it easier to import foreign cars or have American cars manufactured in foreign countries. But if anything, experts says, it’s the fact that other countries have broader free trade agreements that makes places like Mexico an appealing location for an automotive factory.

“We sit here and debate whether we should do trade agreements,” Moutray says. “Meanwhile the rest of the world is aggressive at it.”

And trade deals have made it possible to manufacture some car parts overseas for a fraction of the price. No one would argue this didn't help hasten Detroit’s decline. But if you cite trade as the culprit, you must also cite Detroit's other issues: its drastic population decline that began in 1950, the gasoline crisis of the 1970s that made efficient foreign vehicles more attractive, and the mismanagement of its pension funds.

Experts say you can also argue that Detroit's leaders were delinquent in not diversifying the city's economy sooner, and that the big three auto makers were remiss in not responding quickly enough to foreign competition. "Detroit as a city was killed in part by itself," Macomber says, noting that Detroit invested too much time preserving a single industry and not enough creating new ones. "The big three declined because of productivity efficiencies coupled with complacency about poor quality and variety of product."

The plan Trump has put forth to bring jobs back to Detroit and other American cities risks repeating history's mistakes. Trump may be right about what's ailing Detroit, but cutting off trade is not the remedy.