Since the Reconstruction Act was signed in 1867 the government tried to implement a series of attempts to uplift not only southern African Americans but all of them in the US.
First, the most famous attempt was the 15th Amendment to the US Constitution that prohibited the government from states and the federal government to deny a citizen the right to vote, this was the first time African Americans were able to be represented in politics.
The Freedmen’s Bureau was also implemented, it was a government bureau that aimed to help freedmen and white refugees that came to the US. It provided food, clothing and advised people on working contracts for example.
But unfortunately, those policies were not successful. When President Johnson came to power he had different views than Lincoln, he pardoned many Confederate leaders and he did include black in the government as he should.
His policy opened the way for the creation of the Black Codes, that were a series of laws passed by the Southern States. This codes aimed to seize the liberty of ex-slaves by removing their voting rights, rights of property, working rights, lowered their wages, etc. These codes were up until the 1960s.