How did the people of the North interpret Southern Black Codes?

By the end of Andrew Johnson's presidency it was clear that the northern states were growing weary of the Reconstruction quagmire which included the 'Black Code'  legislation that was being passed at the state level. These codes were legislated for the sole purpose of depriving the newly freed slaves of their Constitutional rights ratified by the 13, 14, and 15th Amendments.  Between 1865-1877 many northern states had shifted their attention away from Reconstruction to concentrate on their industrialization. The business of making money usurped the noble cause of reconstructing the south. Moreover, and perhaps even hypocritical was the de-facto segregation that existed between the newly freed African Americans and the European immigrants in the north. Apparently the white immigrant was perferred over the American counterpart with regard to the hiring practices in the northern factories. Unfortunately the 13,14,and 15th Amendments had little bearing upon the quality of life for the African American in a post Civil War America. It must be noted that the emerging indifference of the north had the support of the Hayes administration, which in some strange way legitimized the general disinterest. Once the northern state 'allies' of the abolitionist cause got tired of hearing the 'same old story' they left the southern state governments to their own devices. It was only a matter of time before segregation became legal. The 1896 Supreme court case Plessey v. Fergurson ruled separating Americans by race was Constitutional as long as it was equal. The 'Separate But Equal' doctrine remained a part of American life for 58 years. It's a terrible thing when our nation turns a blind eye towards the ills of fellow Americans. This attitude was compounded by the times... northern industrial power, lack of media communication between the north and south, U.S. desire to become an imperial power, WWI, the crash, the depression, WWII, and so on. In other words neither the north or the south cared much, the reality... those disenfranchised Americans were on their own...until the re-birth of the Civil Rights Movement of the 1950's-1960's.