On May 26, 1967, Kay E. Whitfield of Pontiac and Noreen E. Hillary of Grand Rapids became the first two women sworn in as officers in the Michigan State Police.
Source : Detroit Historical Society Facebook page
For more information about women police, see
“Two Tough Troopers”, Battle Creek Enquirer, May 27, 1967, p.1
Breaking the brass ceiling : women police chiefs and their paths to the top / Dorothy Moses Schulz.
Police women : life with the badge / Sandra K. Wells and Betty L. Alt.
Women and policing in America : classic and contemporary readings / [edited by] Kimberly D. Hassell, Carol A. Archbold, Dorothy Moses Schulz.