Other districts will see a variety of offices on the ballots -- from judges to justice of the peace -- but everyone will see "State Senator" on the ballot.
For the first time, U.S. Senator Mitch McConnell has a major opponent on the Republican ballot in Matt Bevin.
The two spent Monday blitzing through the state to bring in votes.
But Bevin insists McConnell won't make it to the fall election; he expects to pull the upset because the same polls that show him trailing in the race also show dissatisfaction with McConnell.
"Those very same polls show that there's somewhere between a 30- and 38-percent approval rating for Mitch McConnell, and that's every one of those polls that's been taken for the last two years. So, people are weary. They're fatigued of him," said Bevin.
But the question for Bevin is whether Republicans are fatigued enough to replace the man who could be the next Senate Majority Leader.
"We'll find out," Bevin said. "Because, I'll tell you, if there's not, then we are going to lose this seat. The odds of us keeping this seat in November with the absolute dispassion that exists for Mitch McConnell is slim to none."
Democratic front-runner Alison Lundergan Grimes is already looking ahead to the fall. She has been speaking out against Senator McConnell, promising to bring progress to Kentucky.
Some voters at the Mary T. Meagher Center in Crescent Hill told WDRB's Rachel Collier said it took them less than five minutes to cast their ballots.
"It might just be a primary, but it's the one way we still have a say in our government," said David Stanley. "So I always make sure I exercise that right."