Why did slavery start to expand so much from 1840 to 1860?

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Slaves provided free labor to those who owned them. The increased demand and prices for cotton led to plantation owners to search for land in the west. The result was an explosive growth in demand for slaves in cotton cultivation. Slave trade had become a major economic activity in the South.

explanation:

the addition to geographic boundaries that might have  kept the people of the huang river civilization from traveling to far distance region is that they had learned about the other river valley civilizations but feared contact would bring invasion.

hope this .

plz give me brainliest!

sitting in that one chair where he could get shot at was his worst decision.