1. The biggest issue dividing the U. S. in the years leading up to the Civil War was . 2. in the north wanted to abolish it.
3. in the south wanted to preserve it and increase states’ rights.

Answer choices:
Democrats Republicans slavery

1. Slavery

2. Republicans

3. Democrats

Explanation:

Slavery is the main reason the states fought and was a prevalent issue in the states for a long time mainly starting at the 3/5ths compromise. The two parties of Republican and Democrat were origianlly created as a single party, lead by Thomas Jefferson and James Madison, but were split into the Whig Party and The Democrats after a political division inside the party about the election of 1824. In the mid-nineteenth century the Democrats were split on the issue of slavery and eventually the Democrats in the north (+ the Whig Party and some other politicians) joined together to make a new Republican party that was against slavery (leaving the southern Democrats as pro-slavery).

boundary is what it refers to hope this

explanation: