What is the central idea in the underground railroad? Cite specific evidence from the text to support your answer.

The central idea of the Underground Railroad is Cora who seeks to find freedom.

Explanation:

The central idea of the Underground Railroad is Cora who seeks to find freedom. Cora and Caesar find supposed freedom in North Carolina, only to discovered that they are not yet free, because the government makes birth control mandatory and unethical medical studies is done on the black population.

Cora technically is free from slavery, but still not allowed to move around freely or do as she wishes.