In 1961, Ronni Solbert was living with her partner, Jean Merrill, on the north side of Tompkins Square Park, in Manhattan’s East Village, alongside the immigrants and bohemians who defined the neighborhood’s idyllic, small-town-in-a-big-city vibe.
When the city’s Parks Department announced plans to tear out many of the park’s benches, chess tables and centenarian trees to make room for a softball field, the neighbors rose in oppositionwriting letters, organizing protests and forming the Committee for the Preservation of Tompkins Square Park.
They won their fight, at least in part, and in doing so helped inspire Ms. Solbert, an illustrator, and Ms. Merrill, an author, to write a young adult novel, as Ms. Solbert explained in 2014 to The Valley News, a newspaper covering parts of Vermont and New Hampshire (by then she had moved to Vermont). The two had already published several books together and would collaborate on 18 in all, but “The Pushcart War,” published in 1964, was their greatest achievement.
The story revolves around a ragtag band of pushcart vendors who go to war against the fleets of trucks taking over their narrow city streets, most memorably by attacking enemy vehicles with pea shooters. A modern-day parable of underdogs taking on bullies, it quickly found millions of readers.
Ms. Solbert, whose death on June 9, at 96, was not widely reported, credited Ms. Merrill, who died in 2012, as the book’s main creator. But Ms. Solbert’s illustrations, at once urbane and emotional, very much in the vein of midcentury New Yorker cartoons, were likely to have contributed to its rapid elevation into the pantheon of children’s literature.
Her niece, Lisa Solbert Sheldon, said Ms. Solbert died at her home in Randolph, Vt., where she and Ms. Merrill had moved in 1970.
Among the many fans of “The Pushcart War” was the playwright Tony Kushner, who at one point hoped to adapt it as a screenplay and later wrote a blurb for an edition published by The New York Review of Books in 2014.
“The book gave me a point of entrance — my first, I imagine — into the world of resistance to political and economic injustice and chicanery,” Mr. Kushner wrote. “It made opposition, even nonviolent civil disobedience, seem fun and right and necessary and heroic, and something even someone as powerless as a kid could and should undertake.”
Romaine Gustave Solbert, who went by her childhood nickname, Ronni, was born on Sept. 7, 1925, in Washington. Her family soon moved to Rochester, NY, where her father, Oscar Nathaniel Solbert, was the first director of the George Eastman Museum of photography and film. Her mother, Elizabeth (Abernathy) Solbert, was a homemaker.
Ms. Solbert graduated from Vassar College in 1946, and received a masters in fine arts from the Cranbrook Academy of Art in Michigan in 1948. After a few years working in Sweden, where her father had been born, she moved to New York City to pursue a career in art.
She followed two paths. She painted, mostly in the vein of Abstract Expressionism, and was fairly successful, with 17 of her works included in the Museum of Modern Art’s “New Talent” exhibition in 1959.
She also began illustrating children’s books. She met Ms. Merrill soon after arriving in New York, and they released their first book together, “Henry the Hand-Painted Mouse,” in 1951. They went on to collaborate on 17 more, including “The Pushcart War.”
Critics noted how much Ms. Solbert’s work elevated Ms. Merrill’s texts, many of which told complex stories about outsiders fighting bureaucratic conformity.
Reviewing their 1969 book “The Black Sheep” for The New York Times, Natalie Babbitta noted children’s book author and illustrator, praised the way “Jean Merrill pulls off a difficult thing very well with the assistance of Ronni Solbert’s carefully careless, waggish drawings.”
Ms. Solbert worked with other authors as well. She illustrated the poet Gwendolyn Brooks’s “Bronzeville Boys and Girls” (1956) and “The Two Runaways” (1959) by Aline Havard. She also wrote three books of her own.
Ms. Solbert and Ms. Merrill bought a farm in Washington, Vt., in 1962. They left New York for good eight years later, having watched their beloved Tompkins Square Park fall into disrepair and crime overtake the East Village.
“You found yourself trying to spend more time trying to fix things, but the problems were too big,” Ms. Solbert told The Valley News in 2014.
In 2013, a year after Ms. Merrill’s death, Ms. Solbert, who leaves no immediate survivors, gave their farm to the Vermont Institute of Natural Science and settled full time in Randolph, a small town in the center of the state. She had largely stopped illustrating but continued with her art, which by then included photography and sculpture.
“Art is my sanity, joy, frustration and passion,” she wrote in an artist’s statement. “My subject is the human animal, our relationship with each other and to the world we inhabit. I want the work to invite reflection, open perspectives and challenge the viewers’ emotional and intellectual responses.”