Mary Bruecken is named in a 1922 history of the Pittsburgh Red Cross as a nurse who was "in active service with the American Expeditionary Forces and in the United States." The Department of Veterans Afairs Death File indicates that Mary Bruecken served in the military, presumably the U. S. Army, from March 28, 1918 through January 30, 1919. She re-enlisted April 1, 1918.

In 1930, Mary, a nurse, was living in the family home on Troy Hill Road, with her parents, Jacob P. and Anna C., as well as siblings, Gilbert A., Raymond G., and Armilla G.

Mary was born on April 22, 1894 and her death occurred on November 15, 1974 in Pittsburgh. She is buried at Christ Our Redeemer Cemetery, Pittsburgh.