When most people think of first ladies who were activists, they look to women like Eleanor Roosevelt, Laura Bush, and Michelle Obama. But, women like Florence Harding, Nellie Taft, and Ellen Wilson warrant greater attention for how they challenged the status quo. We spoke with Dr. Katherine Sibley, author of First Lady Florence Harding: Behind the Tragedy and Controversy about how the early 20th century first ladies paved the way for those to follow.