Besides mathematics, Cox also took courses in German, English, Latin, history, hygiene, chemistry, education, philosophy and physics. Cox's brother Avalon was at Indiana University as well. There were three other black students in his class. He received his bachelor's degree in 1917, at a time when the transcript of every black student had the word "" printed across it. After he graduated in 1917, Cox joined the U.S. Army to fight in France during World War I. After he was discharged from the Army, he began his career as a high school math tutor. After the war he returned to pursue a career in teaching, as an instructor of mathematics at a high school in Henderson, Kentucky. In December 1921 he applied for admission to Cornell University, one of seven American universities with a doctoral program in mathematics. One of his references wrote a positive letter followed by another letter anticipating difficulties for him because he was a "colored man". Cox was awarded his PhD by Cornell in 1925, for his dissertation, The polynomial solutions of the difference equation af + bf = φ.
On 16 September 1925, Cox began teaching mathematics and physics at the then all-black, poorly funded West Virginia State College. Professors with a PhD were rare there, and his international connections made him stand out as well. He received a salary of $1,800. His influence can be seen in the large number of changes in the curriculum between 1925 and 1928. In 1927, he married Beulah Kaufman, the daughter of a former slave. She was a teacher at an elementary school, and worked with Cox' brother Avalon. He and Beulah had met in 1921 and had courted for six years. Their first child, James, was born in 1928. In 1929, he joined Howard University and moved to Washington, D.C..
Howard University
Cox started to teach at Howard University in September 1930. Despite his credentials, he was outranked by other professors such as William Bauduit and Charles Syphax. Both had published multiple papers; it was only now that Cox published his graduation paper. Williams, his supervisor, tried to pursue recognition for Cox from a university in another country, but had difficulties in doing so. Different universities in England and Germany refused to consider his thesis, but the Tohoku Imperial University in Sendai, Japan did recognize it. It was published in the Tôhoku Mathematical Journal in 1934. He was, however, very active in teaching: the university's president, James M. Nabrit, remarked that Cox had directed more Master's Degree students than any other professor at Howard University. His students also performed better than those of other professors, and he was a popular professor. Among his students was his son Elbert Lucien Cox, and William Schieffelin Claytor, the third African-American to get a PhD in mathematics. Cox was promoted to professor in 1947. In 1954 he became head of the Department of Mathematics, a position which he held until 1965, when he retired at the age of 70, three years before his death. He spent most of his life as a professor at Howard University. His portrait hangs in Howard University's common room. During his life, Cox published two articles. He expanded on the workNiels Nörlund had done on Euler polynomials as a solution to a particular difference equation. Cox used generalised Euler polynomials and the generalised Boole summation formula to expand on the Boole summation formula. He also studied a number of specialised polynomials as solutions for certain differential equations. In his other paper, published in 1947, he mathematically compared three systems of grading.
Honors
The National Association of Mathematicians established the Cox-Talbot Address in his honor, which is annually delivered at the NAM's national meetings. The Elbert F. Cox Scholarship Fund, which is used to help black students pursue studies, is also named after him. Mathematician Talitha Washington championed Cox leading to the November 2006 unveiling of a plaque in Evansville commemorating his pioneering achievement.
Family
Elbert and Beulah Cox had four children: James born 1928, Eugene Kaufman born 1930, Elbert Lucien born 1933, and Kenneth, born 1935 but died at the age of 17 months.
