GROWING up in the 1970s and ’80s in the Chicago suburb of Blue Island, Ill., Gladys Marquez, the daughter of Mexican immigrants, never once had a Hispanic teacher. Sometimes, when trying to explain to her parents her plans for college — or even why she wanted to play softball or try out for the cheerleading team — she wished she had a mentor who shared her background.

“It would have been nice to have a teacher in the classroom who could help you bridge over and help you become a better version of yourself,” she said in a recent interview.

Now Ms. Marquez is herself a high school teacher in Blue Island. But while nearly half of the students at the school are Hispanic, Ms. Marquez is still one of a small minority of Latino teachers in the building.

Across the country, government estimates show that minority students have become a majority in public schools. Yet the proportion of teachers who are racial minorities has not kept up: More than 80 percent of teachers are white.