African Americans gained significant political participation when amendments were added to the Constitution, particularly with the passage of the 13th, 14th, and 15th Amendments. These amendments abolished slavery, granted citizenship, and protected the right to vote for men regardless of race, respectively.
While other groups have also experienced changes in political participation over time due to various amendments and legislation, the most direct constitutional amendments that expanded political rights at the national level primarily affected African Americans during the Reconstruction era.
It should be noted that Native Americans, Asian Americans, and Hispanic Americans have also struggled for and gained rights over time, but the amendments specifically aimed at addressing issues of race and voting directly impacted African Americans more profoundly in the context of the Constitution.