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.