Series I. Correspondence documents Parker's relationships with publishers, with his collaborator Helen Hokinson, and with his family. A significant volume of letters and postcards to his wife document his experiences in Washington, D.C. during World War II. Correspondence with Helen Hokinson includes a series of postcards from Parker containing ideas for captions and cartoons gleaned from overheard conversations on a trip to California, Seattle, and Alaska in 1938. Correspondence with The New Yorker includes pay stubs and contracts.