Controversies
As a professional cartoonist he started relatively late. His crude black humor and the topics he dealt with raised not a few controversies, some publications where he appeared received phone calls from advertisers threatening to withdraw their advertising.
The cartoonist also received mail and letters, some of these complaints are collected on the author's website in a section entitled "Hate Mail from America".
In 1996, Callahan sent a cartoon about a teenage Martin Luther King Jr. to the Miami Herald that was instantly rejected as obscene.
However, something unexpected happened. During the layout, a worker mistakenly included it for publication and the Miami Herald had to destroy 500,000 copies of the newspaper. That day, the newspaper decided never to publish Callahan's cartoons again.

The cartoon in question is entitled: Martin Luther King, 13 years old.
The scene shows an angry looking woman at the door of her son's room.
A young man is standing by his bed, over which there is a puddle. The young man says:
"I Have a Dream"
The cartoonist always stood his ground on the criticism he received. In an interview in 1992 with the New York Times he said:
"The only compass I can use to know if I have gone too far is the reaction I get from people in wheelchairs, or with hooks instead of hands.
"Like me, they are sick and tired of people telling the rest of the world how to talk about cripples: with false compassion and paternalism. That is what is truly detestable."
Despite this, it managed to be syndicated in a number of publications.
He also gained the attention of editors and the admiration of different artists and famous people who praised his work such as the comedian Richard Pryor, the illustrator Bill Plympton, the cartoonist Gary Larson and even Bill Clinton.
When Callahan was celebrating his 27 years as a cartoonist, he received praise from the creator of the Simpsons, Matt Groening, who said that Callahan's works were:
"Rude" and "depraved", in short, all the adjectives that cartoonists want to hear. "
A park to remember John Callahan
Facebook group of friends and family of John Callahan. In 2014 they promoted the construction of a memorial park in the Northwest District, Portland (I don't know if they succeeded)

One of the initial ideas for the memorial park remembering John Callahan.
Update July 2017, work begins on the future Jhon Callahan Memorial Park/Garden
Location in Google Maps

The John Callahan Garden opens on 27 October 2017

Photo: FB group John Callahan Cartoonist

Photo: Roodney Red

Related:
2020 - Remembering John Callahan: Our coverage of his life and death ten years later, from Oregon Music News.