U.S. Constitution - 15th Amendment

The 15th Amendment to the U.S. Constitution granted African-American men the right to vote, in 1870.  This is its text:

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.

NOTE that "gender" is not included in the amendment.  That issue was resolved by the 19th Amendment which was ratified on August 18, 1920.