Final answer:
The problem that led to the Civil War was slavery.
Step-by-step explanation:
The problem that led to the Civil War in the United States was slavery. Slavery became a major point of contention between the Northern states, which were increasingly abolitionist, and the Southern states, which relied on slave labor for their agrarian economy. This issue ultimately led to the secession of Southern states and the formation of the Confederate States of America, resulting in the Civil War.
Learn more about Causes of the Civil War