Ohio produces more internal combustion engines than any other state, making an adjustment to electric cars particularly urgent. Nearly 90,000 people work in Ohio for carmakers or parts suppliers, and several times that many are employed by businesses that serve those autoworkers and their families.

The changes are putting Ohio at the forefront of a new technology that is critical to fighting climate change. But some jobs will become obsolete, and some companies will go bankrupt. It’s an open question whether the winners will outnumber the losers.

“This is the largest transition in our industry since its inception,” said Tony Totty, the president of a United Auto Workers local that represents G.M. workers in Toledo.

Mr. Totty is optimistic about the members of his local. But he is worried about other colleagues whose jobs are tied to gasoline engines, he said.