What was the 2nd compromise before the civil war for slavery?

Slavery played the central role during the American Civil War. The primary catalyst for secession was slavery, especially Southern political leaders' resistance to attempts by Northern antislavery political forces to block the expansion of slavery into the western territories.

they required less loading and unloading

explanation:

the shipping container improved shipping because it cut down on unloading time by three weeks, eliminated wasted space, and allowed ships to carry.