The number of black public school teachers in nine cities — including the country’s three largest school districts — dropped between 2002 and 2012, raising questions about whether those school systems are doing enough to maintain a diverse teaching corps, according to a new report to be released Wednesday.

The study by the Albert Shanker Institute, a think tank funded by the American Federation of Teachers, looked at teacher data from nine cities: Boston, New York, Los Angeles, Chicago, Cleveland, New Orleans, Philadelphia, San Francisco and Washington, D.C. The research found that each city saw a drop in the number of black teachers in traditional and charter schools.

The issue of teacher diversity is important because research has suggested that students who are racially paired with teachers — black teachers working with black students and Hispanic teachers working with Hispanic students — do better academically. Teachers of color also can serve as powerful role models for minority students, who are more likely to live in poor neighborhoods than white students and less likely to know other adults who are college graduates.

“Diversity is a key component to equality and opportunity,” said Randi Weingarten, the president of the teachers federation, who is asking the Obama administration to call a White House summit on teacher diversity. “Where there’s a diverse teaching workforce, all kids thrive. That’s why we note with alarm the sharp decline in the population of black teachers in our cities.”

Researchers examined the decade between 2002 and 2012 because it was a period of rapid expansion of public charter schools and closures of traditional district schools. There also were other state and federal policy changes, such as the use of teacher evaluation systems, that caused some churn and upheaval in teaching ranks.

The largest drop took place in the District, where between 2003 and 2011, the portion of the D.C. teaching force that was white more than doubled from 16 percent to 39 percent while the share of teachers who were black shrank from 77 percent to 49 percent. During the same period, the percentage of Hispanic teachers increased slightly.

In New Orleans, where 7,000 teachers lost their jobs in the wake of Hurricane Katrina and traditional schools were replaced by public charter schools, the share of teachers who were black fell from 74 percent before the storm to 51 percent in 2012. During the same period, the share of teachers who were white grew from 25 percent to 43 percent.

“It wasn’t until we did the study that I realized it was a fairly significant issue and that it’s true in virtually every city,” said Leo Casey, executive director of the Shanker Institute. “We just had no idea the extent of it. What’s clear from this data is over the last 10 years or so with the recession, if you look at every one of these cities, there’s a loss of teachers — but African Americans are bearing a hugely disproportionate share of the loss.”

One bright spot was Los Angeles, where the number of its Hispanic teachers has jumped in both traditional public schools and public charters.

Nationally, school districts have been doing a good job of attracting black, Hispanic and Asian teachers. But they are disproportionately assigned to high-poverty, struggling schools, and they leave the teaching ranks at a faster rate than white teachers, according to Richard Ingersoll, an expert who teaches at the University of Pennsylvania.

“The whole effort of the last two decades has been toward minority-teacher recruitment, and it’s been an unheralded victory, really,” said Ingersoll, who has been researching the changes in the country’s teaching corps of nearly 4 million. “The problem is with retention. Minority teachers have significantly higher quit rates than non-minority teachers. And that’s a huge problem.”

Minority teachers quit because of working conditions in their schools, Ingersoll said. In surveys, those teachers cite lack of autonomy and input into school decisions, common complaints in struggling schools that have been placed under prescriptive “turnaround” models, he said.

“With accountability, often you have a standardized curriculum that’s scripted and sometimes micromanaged,” Ingersoll said. “There are certainly some positives, but the downside is it drives teachers nuts. . . . What I always suggest is that we hold people accountable for results but then get out of their way. It’s not the way we treat teachers in these large urban districts.”