The declared that slavery in the new territories would be decided by popular sovereignty

I am certain that the answer is the Kansas-Nebraska Act

The Kansas-Nebraska Act replaced the Missouri Compromise of 1850, which basically stated that for every free state submitted, a slave state would be submitted as well to keep the balance of slave and free states. 

The Kansas-Nebraska Act replaced that by stating that slavery in all of the new territories would be decided by popular sovereignty, which is simply put as, decided by the people.

I hope this helped!! Have an amazing day :)) 

In financial aspects, a depression is a sustained, long haul downturn in monetary movement in one or more economies. it is a more extreme monetary downturn than a recession, which is a slowdown in financial action through the span of a typical business cycle. a depression is an irregular and extreme type of recession. so depression is always followed by recession but it is not correct to state that a depression always follow a recession.