This statement is false. The KKK actually came back to power in the 1920s. It had essentially been dead from the time that Reconstruction ended. But then it came back to life again during the 1920s.
There are some strange things about this KKK revival.
First of all, much of its power was in the North rather than in the South where we always think of the KKK being centered. They even had one of their members who became the governor of Indiana.
The other strange thing is that the KKK was not really anti-black at this point. Instead, they were mostly opposed to immigrants, Jews and Catholics.