Thomas Peterffy, Florida
Peterffy's $18.8 billion comes from discount brokerage in Palm Beach. He founded Interactive Brokers, which is a sophisticated trading platform. He also owns more than 500,000 acres of timberland. He arrived in America in 1965 after moving here from Hungary.
Jim Kennedy, Georgia
Kennedy's $9.2 billion is credited to both the media and automotive industries. He is the chairman of Cox Enterprises in Atlanta, and his grandfather founded the company in 1898 following a purchase of the Dayton Evening News.