Why did voting rights become a central issue in the Civil Rights Movement?

Because blacks weren't allowed to vote. The right to vote was pretty much a spark for the rest of the demands that Blacks wanted from their government. They only wanted to be seen as equal with the Whites.

Explanation:

Many African Americans who attempted to vote were also threatened physically or feared losing their jobs.

Explanation:

When Reconstruction ended in 1877, states across the South implemented new laws to restrict the voting rights of African Americans. These included onerous requirements of owning property, paying poll taxes, and passing literacy or civics exams. Many African Americans who attempted to vote were also threatened physically or feared losing their jobs. One of the major goals of the Civil Rights Movement was to register voters across the South in order for African Americans to gain political power. Most of the interviewees in the Civil Rights History Project were involved in voter registration drives, driving voters to the polls, teaching literacy classes for the purposes of voter registration, or encouraging local African Americans to run as candidates.