Jenkins was the son of a prominent Kansas City minister, war correspondent and newspaper editor. He was a popular sports cartoonist, whose work appeared in the New York Journal-American from 1931. His humorous published verses were also popular. Although best known for his sports themes, Jenkins was also a skilled courtroom illustrator and editorial cartoonist. He was fired from his first job at the Kansas City Post for a series of pessimistic Christmas cartoons, a firing which prompted his father's resignation from the same newspaper. Among his best-remembered cartoons are his angry piece on the discovery of the dead Lindbergh baby, and his sentimental image of Babe Ruth's farewell to Yankee Stadium.