Of the 275K I wouldn’t be surprised if most (who didn’t die) simply left the state. There’s very little to stay for. I left when I went to college. My brother (only sibling) left when he graduated from college. My parents left when my father retired (which was as soon as he could). Oh, and my wife, who I met in Connecticut, also left to go to college elsewhere.
Since 1970, the population growth from census to census is only around 2 or 3% per decade.
“Ohio’s population has stagnated, growing slower than 38 other states” according to: