Mary McDade was born in Columbia, South Carolina in 1939, but grew up in Ann Arbor. Her parents Albert and Emma Wheeler were active in local politics and civil rights. As a college student, McDade helped found the University of Michigan chapter of the NAACP. She moved to Peoria, Illinois with her husband Joe Billy McDade in 1963. After raising four children, she built a career in law. McDade graduated from the University of Illinois College of Law and she has been a justice of the Illinois Appellate Court since 2000.