Donald R. McCoy was born January 18, 1928 in Chicago, Illinois. He served with the U.S. Army Signal Corps at the end of World War II, returning to civilian life in 1947. He thereafter received his B.A. from the University of Denver in 1949, his M.A. from the University of Chicago in 1949, and his Ph.D. in 1954 from American Univerity. While working on his doctorate, McCoy worked as an archivist with the National Archives of the United States, in the Department of the Interior's records, and he was on the faculty of State University of New York College at Cortland.

McCoy joined the faculty of the University of Kansas in 1957 in the History Department, reaching full Professor status in 1964. He was named a University Distinguished Professor in 1974 and retired in 1995. McCoy's main research interests were in 20th century United States history, particularly political history and the institution of the U.S. Presidency. His published books include Angry Voices: Left of Center Politics in the New Deal Era, Landon of Kansas, Calvin Coolidge: The Quiet President, Quest and Response: Minority Rights and the Truman Administration, and The Presidency of Harry S. Truman.

At the same time, McCoy held a deep interest in archives and archival work; his book The National Archives: America's Ministry of Documents, 1934-1968 (1973) won him the Society of American Archivists' Waldo Gifford Leland prize. McCoy served on several advisory committees for the National Archives and for the Harry S. Truman and Dwight D. Eisenhower Presidential Libraries. He helped establish the University Archives at the University of Kansas and the master's program in historical administration and museum studies at KU. McCoy also served as president of the Kansas State Historical Society (KSHS) from 1981-1982, in addition to several years of service on the KSHS board of directors and membership on the editorial advisory board for Kansas History: A Journal of the Central Plains>.

Donald R. McCoy died in Lawrence, KS on November 12, 1996.