The U.S. Civil War Pausing Point

I took care of a baby when I was young and escaped from slavery on the Underground Railroad when I was older. Who am I?

I am a very large farm where large amounts of crops are grown. What am I called?

I am the secret way enslaved Africans escaped to freedom in the North. What am I called?

I am an imaginary line between the states of Pennsylvania and Maryland, and I separate where slavery was allowed and where it was not. What am I called?

I was the group of northern states that thought it was wrong for the South to secede from the United States. What am I?

I was the group of southern states that seceded from the United States. What am I?

I am one of the main issues that caused the U.S. Civil War. What am I?

I was elected president because people in the North believed I would not allow slavery to expand. Who am I?