She co-authored numerous foundational studies of nineteenth-century African American history and abolitionism.
[2] A highly respected, interdisciplinary scholar, she was especially well known for groundbreaking work on antebellum Black history and abolitionism.
Much of her work was co-authored with the eminent historian James Oliver Horton, who also was her husband.
[3] She was professor emeritus of history at George Mason University.
[4] Before her retirement, she held the Distinguished John Adams Chair in American History at George Mason, and visited the University of Amsterdam as a Fulbright scholar.