What were some reasons that reconstruction began to "unravel"?

The Reconstruction era is the period from 1863 to 1877 in the history of the United States. Reconstruction ended the Confederation and slavery and provided former slaves with political rights, while dealing with the aftermath of the Civil War.

Reconstruction is widely believed to have failed, for several reasons. One major reason for this was the Southern whites’ backlash that resulted in widespread violence. As the former slave population was granted political rights, in particular the right to vote, white supremacist ideas became more widespread, culminating in the creation of the Ku Klux Klan.

However, even the rights for former slaves were very limited in their scope and irregular in their implementation. The Republicans were unable to effectively guarantee political rights to the black population. Moreover, they were also unsuccessful in guaranteeing them access to land so that they could have their own economic base of power.

President Ulysses S. Grant also had to deal with divisions in government, between those who supported the Reconstruction (mainly Northerners) and those who opposed it (mainly Southerners). This opposition was one of the main reasons for the unraveling of Reconstruction.

nothing certain is known about what happened, but it seems that the country declined gradually, perhaps due to bad government, or, more likely, due to a series of bad harvests, which resulted in widespread and recurrent famine.