What ways did america advance and/or regress (socially, economically, and politically) by 1877?

The year 1877 saw the 'Compromise of 1877' come into effect. This was an informal agreement after the highly contested Presidential elections between  Republican Rutherford B. Hayes and the Democrat Samuel J. Tilden.

The deal had five major points but the most important were the recognition of Rutherford as the President of the United States and the removal of US army forces from former Confederate States.

The period finally ended the 'Reconstruction' but was followed by a quick deterioration of the rights of Black republicans.Discrimination and harassment among black voters became common and by 1905, most black men did not have any say in the State

We can say that by 1877 the United States evolved enough to leave the Civil War behind but was still far behind providing basic human rights to minorities.

The answer is ethnic groups.