COLUMBUS — Ohio voters hard hit by the economic downturn opened their state to casino gambling Tuesday after an expensive campaign promising thousands of jobs. Passage of Issue 3 marked a significant victory for Penn National Gaming Inc. and Cleveland Cavaliers owner Dan Gilbert, who spent nearly $35 million promoting four big-city casinos in Columbus, Cleveland, Cincinnati and Toledo as the Ohio Jobs & Growth Plan. With 91 percent of precincts reporting unofficial results, Issue 3 passed 53 percent to 47 percent. “It’s pretty obvious that the Ohio electorate bought into the whole culture of despair that’s going on with the economy,” said gambling opponent David Zanotti of the Ohio Policy Roundtable. There seemed to be other sentiment in Trumbull and Mahoning counties, where voters disapproved of the ballot initiative. Voters in Mahoning unofficially shot down casino gambling 55.6 to 44.3 percent and in Trumbull, by the slimmest of margins — 1.1 percent — so did voters, 50.