Nathaniel Prentiss Banks began his career in the mills of Waltham, Massachusetts, and later apprenticed as a mechanic. He pursued further education and became involved in the temperance movement. Banks transitioned to public service, working for the Collector of the Port of Boston and eventually entering the state legislature. He became Speaker of the Massachusetts House of Representatives and aligned with the Free Soil Party, shifting to a stronger abolitionist stance. During the Civil War, he was appointed as a major general and played a key role in recruiting and fundraising for the Union. Postwar, he served in Congress, chaired the Foreign Affairs Committee, and advocated for labor reforms and civil rights, including Negro suffrage and the Alaska Purchase.

Nathaniel Prentiss Banks's political career is marked by a unique blend of expansionist economic policies and progressive labor reforms. Banks's support for Manifest Destiny and territorial expansion, including the annexation of British North America and the Alaska Purchase, contrasts with his progressive stance on labor reforms, advocating for shorter workdays and restrictions on women and children's working hours. His ideological agility is further exemplified by his shifting stance on slavery, evolving from a moderate position to a staunch abolitionist. Banks's foreign policy advocacy for Cuban independence and attempts to acquire Caribbean islands reveals a calculated approach to expanding U.S. influence while balancing regional interests.