Slavery was declining (less people used slaves) during the early
1800's in the U. S. What circumstances changed or reversed this
decline. Why was there an increase (more) in the need for slaves in the
South (Think of Cotton production).

The South relied on slavery heavily for economic prosperity and used wealth as a way to justify enslavement practices.

Explanation:

( sorry my answer is short they wont let me do just war so ignore this) xd

the compromise of 1850 was a package of five separate bills passed by the united states congress in september 1850, which defused a four-year political confrontation between slave and free states on the status of territories acquired during the mexican–american war