ANDREW DIEMER is an associate professor at Towson University. He earned his PhD from Temple University and is author of The Politics of Black Citizenship: Free African Americans in the Mid-Atlantic Borderland, 1817-1863, published by the University of Georgia Press in 2016. He lives in Philadelphia.

"The ... story of William Still, an unknown abolitionist who dedicated his life to managing a critical section of the Underground Railroad in Philadelphia--the free state directly north of the Mason-Dixon line--helping hundreds of people escape from slavery"--