Mary was born in Park Hill, in Cherokee County, Oklahoma. Her great-great grandfather was John Ross, the Principal Chief of the Cherokee Nation. In order to attend the best schools, Mary was sent to live with her grandparents in Tahlequah, the capital of the Cherokee nation. At school, Mary was most inspired by seeing fellow Native Americans as her teachers, especially her Cherokee mathematics teacher. Mary excelled at school, and at age 16, she enrolled at Northeastern State Teachers' College in Tahlequah. She received her Bachelor's degree in Mathematics in 1928. Upon graduating, she worked for the Department of the Interior, teaching math and science in public schools. In 1937, she was assigned to work at the Santa Fe Indian School, one of several government-run boarding schools for indigenous children. Mary was able to provide critically important mentorship and support for these children, as her primary and high school teachers had done for her. 

‍

During her summer breaks, Mary took classes in order to earn a masters degree in mathematics. She valued her education, and took the opportunity to study other subjects that fascinated her, like astronomy. At the time, there weren’t many careers open to women in STEM fields. However, when American men were called to serve in WWII, engineering firms and science labs looked to hire women who were skilled mathematicians. Being hired at Lockheed Aircraft Corporation changed the course of Mary’s career. Mary started as a mathematical research assistant, in 1942, and showed so much promise that she was asked to stay on at the company when the war ended. In 1952, Mary was one of the founding members of the Advanced Development Projects group, sometimes known as Skunk Works. While much of the work she did in this group is still top secret, Mary helped determine the technical requirements for space travel, mapped flight paths to Venus and Mars, collected data that helped design fighter jets for the US Air Force, submarine-launched missiles, and some of the first spaceships. Specifically, Mary used her deep knowledge of mathematics to focus on the effect of Aerodynamics (the Physics of Air) on these aircrafts.