Nelson left Northern Illinois to become the University of Iowa's first athletic director in 1910 and served in that capacity until leaving for World War I in 1917. He was the athletic director at Purdue University from 1919 to 1930 and at Lehigh University from 1934 until he retired on February 11, 1939. Nelson died at the age of 64 on November 23, 1945 at his home in Central Lake, Michigan.