Spruill is the author or editor of six books on woman suffrage including the first edition of One Woman, One Vote: Rediscovering the Woman Suffrage Movement (NewSage Press), the companion volume to the PBS documentary One Woman, One Vote.

Most recently, Spruill wrote Divided We Stand: The Battle Over Women's Rights and Family Values That Polarized American Politics (Bloomsbury 2017). In this book, she addresses the rise of the modern women's rights movement to a peak period of success, the mobilization of social conservatives in opposition, and the impact on American political culture. Other edited works on suffrage include VOTES FOR WOMEN! The Woman Suffrage Movement in Tennessee, the South, and the Nation (University of Tennessee Press).

Spruill is also the author of New Women of the New South: The Woman Suffrage Movement in the Southern States (Oxford University Press). She also co-edited a two-volume textbook on the history of the American South and two multi-volume anthologies about the "lives and times" of women in South Carolina and Mississippi. Spruill was the historical consultant for the HBO movie Iron Jawed Angels and has been an advisor to several museums, including the National Archives for its exhibit, "Rightfully Hers," celebrating the ratification of the Nineteenth Amendment.

Spruill's work has been supported by fellowships from the Radcliffe Institute for Advanced Study at Harvard University, the Woodrow Wilson International Center for Scholars, and the National Endowment for the Humanities, and a research award from the Gerald R. Ford Presidential Foundation. She spent a year at the National Humanities Center.

During her career, Spruill was a professor at the University of Southern Mississippi, Vanderbilt (where she was an Associate Provost) and the University of South Carolina. Recently retired, Spruill lives in South Carolina where she continues to write and consult on a variety of projects.