Significant Event Ending Reconstruction

By the mid-1870s, the United States was grappling with the consequences of the Civil War and Reconstruction. The Reconstruction era aimed to restore the Southern states to the Union, provide rights to freed slaves, and rebuild the South's economy. However, by the end of the decade, this period faced significant challenges and ultimately led to its decline. Which of the following events is widely regarded as a significant turning point that effectively marked the end of Reconstruction?