What were 3 reasons that African Americans's voting numbers increased?

You might think that the numbers of black voters in America rose soon after the Civil War; however, this was not the case for several decades. Even though black men got the right to vote when the 15th Amendment was ratified in 1870, it took a long time for African American voters to turn out. First, only black men could vote at this time (women could not vote until the 19th amendment was passed in 1920). Also, in some areas, especially the South, many African Americans suffered intimidation, violence (including lynching), and racial discrimination, especially when attempting to exercise their voting rights. As a result, only 3% of voting-age black men and women in the South were registered to vote in 1940.
Here are some reasons voting numbers increased:
In the 50 years following the end of Reconstruction after the Civil War, African Americans moved north and west, driven by the racially biased social conditions of the South; this exodus is known as The Great Migration. This caused a shift in electoral power within the United States. For the first time since Reconstruction, greater numbers of African Americans could exercise their right to vote without feeling the sting of Southern discrimination. Black political leaders began to be elected, giving more power to the African American electorate nationally.
The civil rights movement in the 1950s was also a big factor. Facing enormous hostility, black people in the South began to organize to demand their constitutional rights, including the right to vote. They launched voter registration drives in many Southern communities, which caused voter turnout to rise.
More recently, a new poll by the independent political organization BlackPAC found that black voters have seen an increased trend toward racism over the past few years, with 89% believing racism has gotten worse in the United States since 2016, and over half of black voters feel that a renewed attack on black Americans is one of the key shifts in American politics. This is bringing them out to vote.
https://www.crf-usa.org/black-history-month/race-and-voting-in-the-segregated-south

https://www.loc.gov/teachers/classroommaterials/presentationsandactivities/presentations/immigration/african7.html

https://www.theatlantic.com/politics/archive/2018/05/what-black-voters-want/559775/