I'm almost sure it was the Ohio, but that was only on the east side of the Mississippi.
The Ohio River
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
The "Border States" were slave states.
im pretty sure it was the Missouri compromise.
slave states
15 slave states and 19 free states during the American Civil War
So the balance of slave to free states were equal in congress
It was the southern border of Missouri and was just south of the point where the Ohio River ends.