In the wake of the Civil War, the U.S. transitioned toward a more centralized federal governance structure, moving away from states' rights. The Reconstruction era saw efforts to integrate formerly enslaved individuals into society and political processes, leading to passage of the Fourteenth and Fifteenth Amendments, which aimed to secure citizenship and voting rights for African Americans. However, these advancements faced strong resistance, resulting in the imposition of Jim Crow laws in the South. The federal government began to play a more significant role in civil rights enforcement, marking a transformative moment in American history that would shape future governance and civil liberties.