Fifteenth Amendment to the United States Constitution

Adopted on March 30, 1870, the Fifteenth Amendment (Amendment XV) to the United States Constitution granted African-American men the right to vote. It was one of the Reconstruction Amendments.
Background.
Nowhere in the original Constitution or the Bill of Rights were Americans given the right to vote. The Fifteenth Amendment gave African-American men the right to vote. But not until the 1960s did judicial interpretation of the Fourteenth Amendment conclude the right to vote was a fundamental right of all citizens.
The reasons behind the omissions of voting rights in the Bill of Rights and Constitution is that including them would have been too controversial at the time. Each state had different rules for who could vote. Some allowed free blacks the right to vote. Others allowed women the right to vote. A few states required ownership of property in order to vote.
In the Election of 1868, Republican Party candidate, Ulysses S. Grant, won the presidency by only a narrow majority of the popular vote. He received support from free black voters in the South. Without that support, he probably would have lost the election. At the time blacks could not vote in the Northern states. The Republican party needed help to stay in power and thought that black votes would help. At the time Republicans controlled both the Senate and House. The proposed amendment was passed by Congress in 1869 and sent to the states for ratification. It was quickly ratified by three-quarters of the states in early 1870. Part of the reason why is that Republicans also controlled the state governments in the South. Southern Democrats were not able to block the measure.
Results.
After passage, the Fifteenth Amendment did not have much of any impact on black voting in the South for nearly a century. Southerners used various methods including terrorism, poll taxes and grandfather clauses to prevent blacks from voting. Congress and the Supreme Court repeatedly struck down voting restrictions. For example, in a landmark decision in "Smith v. Allwright" (1944), The Court decision made it unconstitutional to keep African-Americans from voting in a Democratic Party primary in Texas. Congress passed the Civil Rights Act of 1957 which stated that all Americans had the right to vote, including African-Americans. But overcoming these problems on a case-by-case basis was proving to be unsuccessful. As soon as one form of discrimination was stopped, a new one appeared in its place. The Voting Rights Act of 1965, removed further barriers to minorities voting. It was amended five times by Congress to extend its protections as needed.