Andrew Carnegie, the 19th century Pittsburgh industrialist, was one of the richest Americans ever, and also a benevolent civic patron. David Nasaw, a self-described "lunatic researcher," wrote a biography simply titled "Andrew Carnegie." Early in December he shared what he learned at the Minnesota Historical Society's History Forum in St. Paul.

Carnegie is credited with leading the steel industry expansion in the United States, persuading manufacturing companies to switch from iron to steel, which was more expensive but more durable. Carnegie operated the companies that built new infrastructure as well as the companies that provided the supplies, Nasaw said, and "that's why Mark Twain calls this a gilded age of corruption." In 1900, Carnegie sold his steel manufacturing company to turn to philanthropy full time, announcing he would give away all his wealth. "And he gives it away in huge quantities," Nasaw said. "Now the question is, why?"