His death was confirmed by the Inquirer, where he worked from 1971 until his resignation in 2012.
"As a cartoonist, he was a gem — a journalist who could evoke reactions from readers ranging from anger and indignation to elation and illumination," said William K. Marimow, the newspaper's editor.
Auth was born in Akron, Ohio, on May 7, 1942, and moved to Los Angeles with his family when he was 9. He graduated from UCLA in 1965, majoring in biological illustration. He was a medical illustrator at Rancho Los Amigos Hospital in Downey before his employment in Philadelphia.
In the meantime, he drew political cartoons for the Daily Bruin, UCLA's campus newspaper, and was encouraged to pursue his craft by Paul Conrad, the longtime cartoonist for the Los Angeles Times.
Auth received a Pulitzer in 1976 and was a finalist for the award twice.
He illustrated 11 children's books.
His survivors include wife Eliza Drake Auth, a painter, and two grown children.