Who is the only person to have won a Pulitzer prize in two consecutive years ?

Nelson Harding (October 31, 1879 – December 30, 1944) was an American editorial cartoonist for the Brooklyn Daily Eagle. He won the annual Pulitzer Prize for Editorial Cartooning in both 1927 and 1928, and as of 2013 was the only cartoonist so honored in consecutive years.The particular cartoon cited in 1928, "May His Shadow Never Grow Less", was a tribute drawn at the end of the 1927 calendar year to flier Charles Lindbergh.
His work was often politically conservative by the standards of his day. He took a leading role in opposition to what some New Yorkers considered to be a threat from Bolshevism in the late 1910s, during the so-called First Red Scare. His cartoons portrayed political radicals as bomb-throwers and terrorists.