Which civil rights tactic was most directly responsible for 18 year olds winning equal voting rights in the 20th century ?

The Voting Rights Act of 1965, signed into law by President Lyndon B. Johnson, aimed to overcome legal barriers at the state and local levels that prevented African Americans from exercising their right to vote as guaranteed under the 15th Amendment to the U.S. Constitution.

it granted civil rights to african americans.

1775 is your answer hope this