Her most notable accomplishments include becoming the first female President of the American Association for the Advancement of Science (1971)[1] and head of the mathematics department of the Office of Naval Research of the US.

[1] Rees was a pioneer in the history of computing and helped establish funding streams and institutional infrastructure for research.

Upon their meeting, they went to Russia together to learn more about their culture, and while on the trip Rees was able to attend a mathematical congress in Oslo.

She received a master's degree in mathematics from Teachers College, Columbia University in 1925, where she also studied law.

At that time, she was told unofficially that "the Columbia mathematics department was not really interested in having women candidates for PhD's".

Her advisor was Leonard Dickson,[7] who agreed to help Rees with division algebra even though he was no longer in the field.

She worked at Hunter High School as an assistant teacher while also attending Columbia University for her master's degree.

[1] Other positions she held include: When working on her PhD at the University of Chicago, Rees was very interested in researching associative algebra.

She was an early proponent of magnetic-core and electrostatic memory, the use of transistor components rather than vacuum tubes, and the design of machines with visual displays and multiple inputs.

No greater wisdom and foresight could have been displayed and the whole postwar development of mathematical research in the United States owes an immeasurable debt to the pioneer work of the Office of Naval Research and to the alert, vigorous and farsighted policy conducted by Miss [sic] Rees.