[DoodleDawg]

2 years, 4 months - Slavery existed under the various flags of the Confederate States of America from 1863 until the war’s end on April 9, 1865

Just over four years - February 1861 to roughly mid-June 1865.

[Ancient Man]

Slavery wasn’t outlawed (by Presidential decree) until January 1, 1863. Thus, 2 years, 4 months.