The answer to your question is,
A. Railroad operations across the nation
-Mabel <3
Even though slavery was abolished, that did not mean the white people would stop treating the black people with a lack of respect. Thus lead to segregation some years later, and then resulted in the civil right movement.
The root cause of the American Civil War is perhaps the most controversial topic in American history. Even before the war was over, scholars in the North and South began to analyze and interpret the reasons behind the bloodshed.
The scholars immediately disagreed over the causes of the war and disagreement persists today. Many maintain that the primary cause of the war was the Southern states’ desire to preserve the institution of slavery. Others minimize slavery and point to other factors, such as taxation or the principle of States' Rights.
In 2011, at the outset of the sesquicentennial, a Pew Research Center poll found that Americans were significantly divided on the issue, with 48% saying the war was "mainly about states' rights," 38% saying the war was "mainly about slavery," with the remainder answering "both equally" or "neither/don't know."
Expansion of Slavery impacted the lives of already enslaved people, by causing them to continue being abused and held as slaves. The expansion further strengthened the practice of slavery, making it even harder for slaves to escape and causing more people to be enslaved too.
