James Edward Day (October 11, 1914–October 29, 1996) was an American businessman and political office-holder.

Day was born in Jacksonville, Illinois, he studied at University of Chicago, where he was a member of Phi Kappa Psi Fraternity, and Harvard Law School, receiving high grades. Following law school, Day joined Sidley & Austin in 1938.

In 1942 to 1945 he went in to military service, after the war he became a businessman also serving as a political office-holder under Illinois Governor Adlai Stevenson as State Insurance Commissioner. In 1961 he became U.S. Postmaster General in the administration of John F. Kennedy. There, he was responsible for reducing the postal deficit through rate increases and for introducing zip codes. In August 1963, he resigned as Postmaster General due to financial difficulties.

After leaving the federal governing he was a moving force in establishing the Washington, D.C. office of Sidley & Austin. Day remained an underwriting partner with Sidley & Austin from 1963 until his resignation in December 1972. Day's departure resulted from a perceived slight by his partners following the merger of Sidley with the Chicago law firm Liebman, Williams, Bennett, Baird and Minow. Day sued his former partners in a case that went to the U.S. Court of Appeals for the District of Columbia. Day v. Sidley & Ausing, 548 F.2d 1018 (D.C.Cir. 1976). The court found that Day suffered from a bruised ego but that the facts failed to establish a legal cause of action.

                       

Courtesy of: http://en.wikipedia.org/wiki/J._Edward_Day