She has wooed several start-ups, persuading them to set up shop in the old foundry building — one with the help of Wisconsin’s governor, Scott Walker, who personally called the co-founders on her behalf.
Ms. Hendricks, a major Republican donor, was briefly thrust into the national spotlight a few years ago when she was recorded asking Mr. Walker to break up the labor unions. He then introduced a bill limiting the ability of public workers to bargain over wages. In response, protesters occupied the halls of the Capitol for weeks.
Not long ago, Beloit’s economy was ugly. Like many American cities — Detroit, Youngstown, Gary — it had fallen victim to the damage that is wrought when one major industry vanishes from town, reversing local fortunes.
Beloit is different today. That’s because this town of nearly 37,000 has a billionaire who has gone to great lengths to help it turn a corner.
In a nation with countless struggling towns and small cities, Beloit is not a model for economic revival that is easily replicated, although a few others have tried.
In Kalamazoo, Mich., a group of well-to-do town “elders” pay for every public school student in town to go to college. And Columbus, Ind., has become an architectural mecca thanks to the support of J. Irwin Miller, whose family made its riches manufacturing engines.
Ms. Hendricks’s project has not been cheap.
Buying and fixing up the foundry alone has cost Ms. Hendricks around $40 million, according to Rob Gerbitz, the president and chief executive of Hendricks Commercial Properties. The Phoenix complex has cost $7 million (with a $1 million assist from the city).
And, of course, money doesn’t solve everything. Ms. Hendricks’s overhaul faces challenges big and small, including skepticism. Early on, some residents joked about giving the city a new name: Hendricksville. Unemployment remains stubbornly high, as does poverty.
Her activities on Beloit’s behalf are complicated by the fact that not everyone agrees with Ms. Hendricks’s political views. She was an early supporter of Donald J. Trump’s presidential campaign here in Wisconsin, a state with a history of progressive politics, and that has pitted her against some current and former students at Beloit College, a liberal arts school and one of Beloit’s other big employers. (Ms. Hendricks sits on the college’s board of trustees.)
“Diane Hendricks is the…