Despite slavery expanding westward with pioneers, which event abolished slavery in the entire United States?

Question

Despite slavery expanding westward with pioneers, which event abolished slavery in the entire United States?

The ending of American Revolution.
The passage of the Thirteenth Amendment.
The issuing of the Emancipation Proclamation.
The beginning of the American Civil War.

Answer 1

The passage of the Thirteenth Amendment abolished slavery in the entire United States. It was ratified on December 6, 1865, following the end of the American Civil War.