llinois' 2018 governor's race was the most expensive in American history. This year's may top it. Since January, three billionaires have thrown $140 million into the mix before Illinois' primary June 28. It's a mounting second round in the state's battle of the billionaires, with eye-popping figures. The hundreds of millions of dollars funneling into the race are, in part, thanks to Illinois’ unique campaign finance laws that trigger a funding free-for-all once one candidate decides to self-fund. The race's outcome could be an expensive lesson in how far money goes in political races. In 2018, multimillionaire Bruce Rauner, a Republican candidate, and J.B Pritzker faced off for governor in a race that cost more than $284 million. Pritzker raised about $175.6 million – mostly his own – and Rauner raised more than $79 million. Primary challengers and third-party opposition raised $29.3 million. Pritzker won the race. Kent Redfield, a professor emeritus of political science at the University of Illinois at Springfield, predicted this year's race could reach $300 million or $400 million before it's settled.