ELI5: How did the american civil war start

The American Civil War started because the Northern and Southern parts of the country lived completely different daily lives and had an enormous argument about whether owning human beings as slaves should be allowed.

Imagine a giant house shared by two brothers who do everything differently:

• The Northern brother worked in busy city factories. His daily life revolved around trains, clocks, and making goods with machines. At the end of the day, workers went home with money in their pockets, and people in the North increasingly believed that everyone should be free to earn their own living.
• The Southern brother lived on huge, quiet farmland called plantations. His entire day-to-day routine depended on growing cotton and tobacco. Crucially, the farm owners forced millions of Black people to do all the brutal, exhausting daily chores—planting, harvesting, cooking, and building—without any pay or freedom.

The trouble grew as the country expanded:

• The North wanted the new neighborhoods to be places where everyone was free and worked for fair wages.
• The South was terrified that losing slavery would destroy their comfortable morning-to-night way of living, like having the roof ripped off their house.
• When a man named Abraham Lincoln was elected president, he promised to stop slavery from spreading to any new areas.