Although Moore's father was reared in
New England and was of New England ancestry, he fought in the
American Civil War on the side of the
Confederacy. After the war, he ran a hardware store in Dallas, then little more than a railway stop, and raised six children, Robert being the fifth.
Moore entered the
University of Texas at the unusually low age of 16, in 1898, already knowing
calculus thanks to self-study. He completed the
B.Sc. in three years instead of the usual four; his teachers included
G. B. Halsted and
L. E. Dickson. After a year as a teaching fellow at Texas, he taught high school for a year in
Marshall, Texas.
An assignment of Halsted's led Moore to prove that one of
Hilbert's axioms for geometry was redundant. When
E. H. Moore (no relation), who headed the Department of Mathematics at the
University of Chicago, and whose research interests were on the foundations of geometry, heard of Robert's feat, he arranged for a scholarship that would allow Robert to study for a doctorate at Chicago.
Oswald Veblen supervised Moore's 1905 thesis, titled
Sets of Metrical Hypotheses for Geometry.
Moore then taught one year at the
University of Tennessee, two years at
Princeton University, and three years at
Northwestern University. In 1910, he married Margaret MacLelland Key of Brenham, Texas; they had no children. In 1911, he took up a position at the
University of Pennsylvania.
In 1920, Moore happily returned to the University of Texas at Austin as an associate professor, and was promoted to full professor three years later. In 1951, he went on half pay, but continued to teach his habitual five classes a year, including a section of freshman calculus, until the University authorities forced his definitive retirement in 1969, his 87th year. In 1973, the University of Texas honored him by giving the name Moore Hall to a new building housing the physics, mathematics, and astronomy departments.
A strong supporter of the
American Mathematical Society, he presided over it, 1936–38. He edited its
Colloquium Publications, 1929-33, and was the editor-in-chief, 1930–33. In 1931, he was elected to the
National Academy of Sciences.