Isaac Asimov's Our Federal Union explores the political and social landscape of the United States between 1816 and the outbreak of the Civil War. Asimov details the growing tensions between the North and South, particularly concerning slavery and the expansion of the Union. He examines crucial events such as the founding of the Second Bank of the United States, the Nullification Crisis, the annexation of Texas, and the Mexican-American War. Asimov highlights key figures of the period, including Andrew Jackson, John C. Calhoun, Henry Clay, and Daniel Webster, and describes the rise of Abraham Lincoln as a national figure. Ultimately, the book explains the seeds of conflict that eventually led to the American Civil War, emphasising the irresolvable differences between the North and South on the question of slavery.