Why did free african americans need certificates of freedom?

Free Black people still faced danger. Many appeared in court to ask for a Certificate of Freedom. The claimant had to prove that he/she was born free or had been previously freed. If the court was satisfied, it would issue a certificate with a minute description of the person including skin shades, hair texture, and body scars. Freedom papers were essential for freedmen who wanted to travel, particularly those working on the rivers.

Explanation:

- "made the south's economy grow rapidly and a small effect that a lot of people don't know is that it made the more demand of slaves and cotton products. and also new states formed due to plantations growing in size."

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the answer is b just took the test