Why was the Voting Rights Act of 1965 necessary?

Because black people had the right to vote it even says under the 15th amendment

The Voting Rights Act of 1965 was necessary because each citizen must be able to participate in government and each citizen must have equal voting power in federal elections.

At the time, a lot of discriminatory actions were taking place. African Americans weren't slaves anymore, but they were still getting treated lke it. They were getting run out of elections by groups of white men, and they weren't allowed in many public places. They began to retaliate, hence Martin Luther King Jr.'s movement. Women, also, were not allowed to vote until 1920, but African American women and Native American women weren't.