Terrorist groups like the KKK were groups of whites who didn't support African Americans having rights. They targeted and killed blacks as a result of the Radical Republicans Freedman's Bureau and addition of the 13th, 14th, and 15th Amendments which gave blacks rights.
Jim Crow Laws
The Jim Crow Laws were put into place in the south which created more racial segregation between blacks and whites.
One of the failures created by the Freedman's Bureau.
Politically, the 13th, 14th, and 15th Amendments were put into place and granted many more people rights in the US.
Political, Social, and Economic Changes
Socially, ways to limit blacks rights like the Black Codes and the KKK developed. Slavery was replaced by racial segregation.
Economically, former slaves were granted jobs that paid and places in Congress as a result of Reconstruction. It took a while, but they were eventually granted these things by the time of Ulysses S Grant's Presidency.