By Quinn Bowman, Terence Burlij and Mike Fritz

Herbert Block, better known as "Herblock," drew his first editorial cartoon in 1929, and over the course of the next seven decades sketched the major events of the second half of the 20th century for the Washington Post. From the Depression to World War II to Watergate, he enjoyed a wide berth of editorial freedom to analyze events and skewer public figures as he saw fit.

That extensive chronicle of commentary is now at the Library of Congress in an exhibition of cartoons, on display until May 1, 2010. The exhibit features thousands of cartoons that date from 1929 to 2001, spanning 13 presidents.

Art Beat talked to Herblock's longtime Washington Post colleague Haynes Johnson, who is also co-author of "Herblock: The Life and Works of the Great Political Cartoonist," Herblock's successor Tom Toles and Library of Congress exhibit curator Sara W. Duke: