Complex sentence: His cartoons were published in "The New Yorker" from 1925--1968 and helped develop the magazine's reputation as a repository for sophisticated humor, often depicting a cross-section of New York society from the 1920s through the 1960s.
Split into simpler sentences: His cartoons were published in "The New Yorker" from 1925--1968. They helped establish the magazine's reputation as a repository for sophisticated humor, often depicting a cross-section of New York society from the 1920s through the 1960s.