GMAS US History EOC Practice Test 2026 - Free US History End-of-Course Practice Questions and Study Guide

The central issue driving the Civil War was the institution of slavery and its expansion into new territories and states. As new areas debated whether slavery would be legal there, the nation faced a fundamental clash over political power, economic systems, and human rights. This struggle shaped party alignments, presidential elections, and legislative compromises for years, making it impossible to pursue a peaceful settlement once secession began. The Mexican-American War did raise the question of how newly acquired lands would be governed, but the deeper, dividing question—whether slavery would continue to spread and how the federal government would regulate it—proved to be the force that led to conflict. While tax policy and regional industry differences created tension, they did not mobilize the country toward war in the way the fight over slavery did.