When did slavery in the United States officially end?

In 1865, the Thirteenth Amendment to the Constitution was passed, abolishing slavery in the entire United States.

The Thirteenth Amendment was the first of the three Reconstruction Amendments adopted after the American Civil War.

Below are the amendments.

Section 1. Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction.

Section 2. Congress shall have power to enforce this article by appropriate legislation.