Final answer:
White citizens post-Civil War policed African Americans to maintain social and economic control and uphold white supremacy through Black Codes and sharecropping.
Step-by-step explanation:
After the Civil War, White citizens were expected to police the activities of African Americans to restore antebellum power relationships and maintain social and economic control. This involved enforcing the Black Codes, which sought to limit the newly gained freedoms of African Americans by imposing severe vagrancy laws, denying the right to serve on juries, and excluding them from public education. Furthermore, to uphold white supremacy, these actions also led to the widespread practice of sharecropping and the establishment of Jim Crow laws, which perpetuated segregation and economic inequality.