KANSAS CITY, Mo. — The Kansas City Board of Education voted Wednesday night to close almost half of the city’s public schools, accepting a sweeping and contentious plan to shrink the system in the face of dwindling enrollment, budget cuts and a $50 million deficit.

In a 5-to-4 vote, the members endorsed the Right-Size plan, proposed by the schools superintendent, John Covington, to close 28 of the city’s 61 schools and cut 700 of 3,000 jobs, including those of 285 teachers. The closings are expected to save $50 million, erasing the deficit from the $300 million budget.

“We must make sacrifices,” said board member Joel Pelofsky, speaking in favor of the plan before the vote. “Unite in favor of our children.”

Mr. Pelofsky and other supporters of the closures made their case with the district’s data: enrollment has declined by half in the last 10 years alone, to 17,400 children, and the schools are only 48 percent full.