Final answer:
The Ku Klux Klan (KKK) used violence and intimidation to restrict the progress of African Americans during Reconstruction, hindering their access to education, voting, and political participation.
Step-by-step explanation:
The Ku Klux Klan (KKK) had a significant impact on the progress of African Americans during Reconstruction. The KKK used violence and intimidation to restrict the rights and freedoms of African Americans. They targeted freed people who tried to improve their lives or participate in political activities, including voting. The Klan burned schools, murdered individuals, and engaged in acts of political assassination to hinder African American progress. Their acts of terror contributed to the collapse of Reconstruction and the reestablishment of white supremacy in the South.