Samuel J. Kirkwood began his career as an educator before transitioning to a prominent role in anti-slavery movements in Ohio. He later moved to Iowa, where he engaged in milling and land speculation. Kirkwood was a founding member of the Iowa Republican Party and held various state and federal positions, including governor of Iowa and U.S. Senator. During the Civil War, he actively supported the Union Army and attended the Loyal War Governors' Conference. Kirkwood's career also included a stint as Secretary of the Interior.

Samuel J. Kirkwood's political career reveals a complex blend of ideological rigidity and strategic flexibility. His staunch anti-slavery stance and active support for the Union during the Civil War underscore a deeply principled commitment to abolition. Yet, Kirkwood's refusal to extradite Barclay Coppock, a participant in John Brown's raid, to Virginia highlights a calculated approach to regional loyalties and justice. His political maneuvers, including serving in both state and federal offices, suggest a politician adept at navigating and leveraging multiple power structures.