CHICAGO (AP) — The 2018 Illinois governor's race is on pace to be the most expensive in U.S. history, propelled by a wealthy Republican incumbent and a billionaire Democrat who are airing TV ads and hopping private planes to campaign events more than a year before Election Day. J.B. Pritzker, an heir to the Hyatt hotel fortune and one of the world's richest people, is among several Democrats trying to defeat multimillionaire businessman-turned-governor Bruce Rauner.