[2] She accepted a National Research Council Fellowship in Physical Anthropology for the 1925–26 academic year, and studied at Oxford University in England, with Arthur Thomson.

As a result of this work, she published her first research paper on bone, "The Moveable Segments of the Vertebral Column in Old Egyptians".

[3] She returned to Washington University School of Medicine the following year and was promoted to assistant professor by Robert J. Terry, the head of the Department of Anatomy.

Cowdry, and being evaluated by a committee,[2] Trotter was finally promoted to full professor of Gross Anatomy, becoming the first woman to hold that rank at Washington University.

[3] In 1948, Trotter was granted a 14-month leave of absence from Washington University, to work with the U.S. Army's Graves Registration Service, at the Central Identification Laboratory at Schofield Barracks in Hawaii.

[1] Frustrated with the lack of recorded data for predicting height and age, she collected her own measurements, building a substantial database of information.

[2][9] In 2022, Routledge published her biography entitled Mildred Trotter and the Invisible Histories of Physical and Forensic Anthropology.