Before the 1960s, images of people of color were rarely included in children's books, and when they were, they were often disparaging caricatures. Peter of The Snowy Day, published in 1962 by Ezra Jack Keats, was one of the first to break that mold. Later, African-American illustrators like Jerry Pinkney would make this genre their own. In the '70s, libraries and schools started to seek out African-American folk tales, like the story of Jake and Honeybunch going to heaven, shown in this illustration from Margot Zemach's 1982 book of the same name. In fact, children's literature moved so far in such a short time that Zemach's celebrated book encountered some resistance from librarians, who feared it might inadvertently reinforce stereotypes by featuring a poor black laborer rather than a more affluent or accomplished protagonist.

Today, the picture book is as malleable and vibrant as it has ever been. Teenagers and adults pore over graphic novels, art media have become stupefyingly diverse, and content for children hops from page to screen and back again. And yet some of the old illustrations still beckon. These pioneering artists figured out what the new work is still searching for: a timeless and consistent way to appeal to a child's imagination.