Philanthropic adviser Jennifer Frutchy said Lewis died at his home in Coconut Grove, Fla.
Progressive President and CEO Glenn Renwick said the company owes its growth and its culture of openness to Lewis. He said Lewis' caring and honesty are "bedrock" values of the company.
"The history of Progressive is very much the history that Peter Lewis laid down," Renwick said. A willingness to take risks and constantly learn and grow are principles that can be traced to Lewis, he added.
"He really was a special person, there's no doubt about that," Renwick said.
Lewis became chief executive officer of Progressive in 1965, built from the company his father co-founded in 1937. Lewis held the leadership post for 35 years, during which Progressive — and Lewis' fortune — steadily grew. In 2006, Forbes calculated his net worth at $1.4 billion.
Lewis turned his wealth into support for a number of progressive causes, including strong support for marijuana law reform that began after he used it following a leg amputation. Lewis helped bankroll marijuana-related causes in Ohio, Washington and Massachusetts.
In a 2011 interview with Forbes magazine, Lewis said he first tried marijuana at age 39. He said he found it to be "better than scotch" and later relied on it for pain management.
"I don't believe that laws against things that people do regularly, like safe and responsible use of marijuana, make any sense," he told Forbes. "Everything that has been done to enforce these laws has had a negative effect, with no results."
Lewis also spent time as a trustee of the Guggenheim Museum and step! ped down in 2005, saying he saying disagreed with the institution's focus on international expansion. He had been a leading benefactor of the museum, donating tens of millions of dollars.
For a time Lewis largely stopped giving to local Cleveland-area concerns, saying there was little cooperation among civic leaders or public development. Last year, however, he donated $5 million to the Cleveland Institute of Art, the Plain Dealer reported. At the time, he said he made the donation because a development plan that impressed him in 2004 had met his expectations.
Lewis also gave generously to his alma mater, Princeton University. He donated more than $220 million to the school, where he also served as a trustee.