America’s so-called “left behind” counties — the once-great manufacturing centers and other distressed places that struggled mightily at the start of this century — have staged a remarkable comeback. In the last three years, they added jobs and new businesses at their fastest pace since Bill Clinton was president.

The turnaround has shocked experts. “This is the kind of thing that we couldn’t have even dreamed about five or six years ago,” said John Lettieri, the president of the Economic Innovation Group, a think tank that studies economic distress in the U.S. His group is releasing a report today that details the recovery of left-behind counties.

Those counties span the nation but are largely concentrated in the Southeast and Midwest. In today’s newsletter, I’ll explain how they defied recent trends — including a particularly grim stretch under Donald Trump — to rebound so strongly from the pandemic recession. I’ll also show the one indicator that helps explain why voters there might not reward President Biden for the good news that has happened on his watch.

Out of the recession

The last two decades were economically cruel for the 1,000 or so left-behind counties in the U.S. — places like Bay County, Mich.; Dyer County, Tenn.; and Lackawanna County, Pa., home to Scranton, Biden’s birthplace. These counties added jobs and people far more slowly than the nation as a whole. Some lost factories to foreign competitors like China. Many lost residents, including educated young workers, as economic activity concentrated in big cities like New York and San Francisco.

As a candidate in 2016, Trump promised to revitalize those areas. In his first three years in office, before the pandemic hit, the national economy was strong. Unemployment was low. Wages were rising. But left-behind counties saw few of those benefits.

In 2018, a colleague and I noted that left-behind counties that voted for Trump had not seen any net job gains the previous year. The new Economic Innovation Group analysis shows that, in terms of job growth, left-behind counties experienced three of their four worst years since the Great Recession on Trump’s watch.

The pandemic recession hit those counties harder than the rest of the country, just as the Great Recession did. But their recovery has been much stronger this time. Left-behind counties added jobs five times faster in the first three years of the Biden administration than they did in the first three years of the Trump administration. The flow of residents leaving them for better opportunities slowed.

Perhaps most strikingly, they have shared in a new-business boom that has swept the country since the pandemic. That didn’t happen after the Great Recession. From 2009 to 2016, for example, Bay County, Mich., lost 8 percent of its business establishments. Since 2020, it has gained 12 percent.

The political fallout

Researchers say it’s too soon to know exactly what’s changed, but there are theories. The pandemic disrupted some long-running patterns of where Americans live and work; some people appear to have fled cities like New York for remote jobs — or for the chance to start a new company — in less expensive areas.

Under both Trump and Biden, the government lavished Americans with pandemic assistance, like direct checks for lower-income and middle-class workers and forgivable loans for business owners. Many people saved that money, and they may have used it to start businesses and create jobs in left-behind counties.

Whatever the explanation, though, Biden probably should not expect voters in those areas to reward him electorally. Many left-behind counties are solidly Republican, or have moved to the right since Trump first ran. And for all their job and business gains, left-behind counties were hurt by high inflation in the early Biden years. In 2021 and 2022, the typical household income in those counties fell, after adjusting for rising prices. Those price increases have left voters unhappy with Biden on the economy, no matter where they live.

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