Shackelford was born in 1905 in Tennessee, the son of John D. Shackelford and Lula May Oliver. He grew up in Prescott, Arkansas, where his father worked as a high school principal and a lawyer. His mother died when he was only four, but his father remarried the next year. Later, when Shackelford was a young adult, he and his family moved to Hot Springs, Arkansas. During the mid-1920s, Shackelford attended
Wiley College in
Marshall, Texas, serving as president of the Alpha Sigma fraternity. As a student, he advocated for literacy among blacks and participated on the school's baseball and basketball teams. He was particularly good at baseball and was selected as the best third baseman in the Southern Athletic Association in 1923. In fact, Shackelford was talented enough play professionally during the summers between semesters with several Negro league baseball teams, including the
Cleveland Browns in 1924, the
Harrisburg Giants in 1925, and the
Chicago American Giants in 1926. Shackelford played with the
Birmingham Black Barons in 1930. After graduating from Wiley, Shackelford moved to
Ann Arbor, Michigan, and studied at the
University of Michigan Law School to become an attorney like his father. He graduated in 1931 and set up a law practice in
Grand Rapids, Michigan. Meanwhile, he both managed and played for various semi-professional Negro teams in nearby
Lowell, Michigan, including the Fineis Gas Colored Giants from 1931 to 1932, the Dixie Gas Stars from 1933 to 1934, and the Chicky Bar Giants in 1935. By 1940, Shackelford moved his law practice to
Cleveland, Ohio. While there, he became involved in Negro league baseball administration. He was nominated for president of the
Negro American League in 1944, but lost the election to
J. B. Martin. The following spring, Shackelford became involved in the foundation of the upstart
United States League and was elected president of the organization. The league operated from 1945 to 1946, but competition from already existing Negro leagues, as well as difficulties associated with wartime economics, ultimately caused it to fail. In addition to serving as president for both seasons the league operated, Shackelford managed the league's Cleveland Clippers in 1946. Shackelford continued to practice law in Cleveland for many years, eventually moving to
Los Angeles. ==Death==