Amendment XV

"Section 1. The right of citizens of the United States to vote shall not be denied or abridged by the United States or by any state on account of race, color, or previous condition of servitude.
Section 2. The Congress shall have power to enforce this article by appropriate legislation."
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U.S. Constitution

Amendments XIII, XIV, XV are known as the Civil War Amendments. XIII abolished slavery, XIV guaranteed and defined citizenship, and reinforcedAmendment V, and XV guaranteed suffrage to all adult male citizens. This radical change aggravated southern whites and inundated the political system with a bounty of new constituents.
From: http://assets.nydailynews.com
From: http://assets.nydailynews.com

Blacks began to exercise their new rights and were elected to offices in the government and community.