John Cornelius Butler graduated from Central High School in Buffalo and began his career as an electrician on the city's Lake Erie waterfront. He was active in various unions, reflecting his commitment to labor issues. Butler spent several years in the private sector, including roles as a sales manager and estimator. He served two non-consecutive terms in the U.S. House of Representatives, during which he opposed the Saint Lawrence Seaway due to its potential negative impact on Buffalo's shipping and cargo industries.

John Cornelius Butler's political identity is marked by an unexpected opposition to the Saint Lawrence Seaway, driven by a staunch defense of regional economic interests. His legislative record reveals a highly localized approach, often prioritizing Buffalo's industrial and shipping sectors over broader national projects. Butler's union background adds an intriguing layer, suggesting a nuanced stance on labor issues that blends ideological consistency with strategic pragmatism. His rhetorical style likely emphasizes the tangible impacts of policy on local communities, making regional concerns central to his political narrative.