Drewry began her career as the head of the history department at Penn Hall Junior College in Chambersburg, Pennsylvania.[4]
In 1936, she joined the National Archives as a reference supervisor. She spent a quarter of a century with the agency, ending her federal career as chief of the records retirement branch of the Office of Records Management. During the 1950s, she spearheaded an effort to introduce a uniform records retention and disposal system.[1][4][6]
Drewry was a specialist in World War I history. Her book, Historical Units of the First World War, was published in 1942 by the Government Printing Office.[1][4] She also served as an adviser to the Thomas A. Edison Foundation.[4]
After Herman Kahn left the Library to take up a post as Special Assistant to the Archivist of the United States, Drewry stepped into the role of Director.[7] She was the first woman to head a Presidential Library, and served there from 1961 to 1969.[1] From 1963 to 1967 she served as a Council Member of the Society of American Archivists (SAA).[8] She was one of only fourteen women to hold an elected office in the SAA before 1972, when the committee on the Status
of Women in the Archival Profession was formed.[9] Drewry was instrumental in the effort to raise funds to expand the Library to house Eleanor Roosevelt's papers; construction was completed in 1972.[1]
After her retirement from the Library, Drewry spent several years as the director of a girls summer camp in Chambersburg, Camp Robin Hood.[4]