This article analyzes the struggle for the control of the American national state during the antebellum period. From this perspective, the secession threat was an important issue for the American state-building process, because the struggle for the control of the national state was a pivotal element of the crises that led to secession and the Civil War. These questions are tackled through the exam of the relations between slavery and the federal system in the context of the crisis of the Second Party System. The departure point of the discussion is the recent debates that assert that slavery and the War were important elements of the American state-building process.