A timeline shows the effects of the cotton gin on the United States.
In 1607, planters began growing cotton in the South.
In 1793, the U.S. slave population reached about 700,000, and Eli Whitney invented the cotton gin.
After 1793, demand for cotton increased in New England mills, and more plantations appeared in Southern states.
In 1860, the U.S. slave population reached about 4 million. In 1861, the Civil War began.
Based on the timeline, what can be directly tied to the invention of the cotton gin?
the Civil War
economic hardships in the South
the spread of slavery
industrialization in New England