In Ohio, persons who will be 18 as of the date of the general election have been allowed to vote in the primary for that general election for several decades. It makes sense that they should be able to and it is up to the state to make that determination.
"17-year-olds can vote in primaries and caucuses in large number of states, including Alaska, Connecticut, Delaware, Hawaii, Illinois, Indiana, Iowa, Kentucky, Maine, Maryland, Mississippi, Nebraska, Nevada, North Carolina, Ohio*, South Carolina, Virginia, Vermont, Washington, West Virginia, and Wyoming. Seventeen-year-olds may also vote in District of Columbia primaries. Most have done this by state law, but others by changing state party rules. "

Here is the Ohio law from 1981
3503.011 Qualifications of electors for primary elections.

At a primary election every qualified elector who is or will be on the day of the next general election eighteen or more years of age, and who is a member of or is affiliated with the political party whose primary election ballot he desires to vote, shall be entitled to vote such ballot at the primary election.


Now explain to me why a GOP secretary of state would say that 17 year olds cannot vote in a primary? Democracy is always advantaged by allowing eligible voters the opportunity to exercise their vote. Sadly that right is now opposed by one party far too often. Every Ohio Sec of State since 1981 has understood the law and allowed 17 year old voters. It was this SOS, Husted, who apparently can't understand the law he is there to administer. And a judge set him straight.