Here are five things to know about the election:
— STATEWIDE RACES: Republican voters will have the final say in two winner-take-all races on Tuesday for insurance commissioner and corporation commissioner, since no Democrats filed for either of those posts. Gov. Mary Fallin will face two pro-marijuana Republicans in that primary. And in the race to become Oklahoma's superintendent of public instruction, four Democrats and three Republicans are vying for their party's nomination.
— INDEPENDENTS LIMITED: Oklahoma has a closed-primary system, so only Republicans and Democrats get to vote in their own party's primaries on Tuesday. Oklahoma's roughly 239,000 registered independents still have a chance to vote on nonpartisan contests for judgeships or various municipal or county elections, but will have to wait for the general election on Nov. 4 to vote in most races. Independent candidates, meanwhile, automatically advance to the general election.
— PRIMARY RUNOFF: If no candidate secures more than 50 percent of the vote in a primary, the top two vote-getters advance to the Aug. 26 primary runoff election.
