Search the Ohio Half Marathon Calendar! Search for your next state of Ohio half marathon at the Ohio Half Marathon Calendar USA website page. The half marathon running event calendar currently has Ohio half marathons 2026 and Ohio half marathons 2027 as they roll in. We strive to have all Ohio half marathon dates posted one year in advance. For races that are late in posting their Ohio half marathon dates, we do our best to update those dates throughout the year, as race dire