I'm almost sure it was the Ohio, but that was only on the east side of the Mississippi.
The "Border States" were slave states.
The Ohio river was important during the civil war. Since most of the states south of the river were slave states and most of the north states were free, many slave crossed the river to try and get freedom.The Tennessee river was a central component of one of the world's greatest irrigation and hydropower systems and a major waterway of the southeastern United States.
California became a free state in 1850, ending the balance of free states and slave states. However, the slave states got a tougher fugitive slave law as a result of California's admission to the Union as a free state.
Because the Louisiana Territory wasn't divided into free or slave states yet.
The Missouri Compromise of 1820 allowed a slave state into the union when alternated with a free state. The compromise allowed Missouri to enter the US as a slave state and part of Massachusetts was divided to allow the entrance of Maine into the US as a free state.
The Potomac divided the Confederacy from the Union, although Maryland was a slave-state, and so was DC at the beginning. The Ohio River divided the slave-states from free soil.
How the land would be divided into slave states and free states.
The Mason &-Dickson line
The Mason-Dixon line
The Mississippi River.
The Ohio
Slaves had to cross the Delaware River to reach the state of Delaware. The river served as a natural barrier between the free states in the north and the slave states in the south.
The "Border States" were slave states.
im pretty sure it was the Missouri compromise.
The Mississippi River served as a significant border between free states and slave states during the Civil War. It was a crucial geographical and strategic divide, influencing the movement of troops and resources. The river's role in commerce and transportation further underscored its importance in the conflict between the Union and the Confederacy.
slave states
15 slave states and 19 free states during the American Civil War