What you say is true. However, you are missing the point,  and you are making the same mistake as Karl Marx by assuming that adherence to the doctrine of a political party will obliterate or exacerbate all areas of social struggle.

While Lincoln did effectuate the emancipation proclamation,  escaped slaves that enlisted in the Union Army during the Civil War were paid less than white soldiers. They also served in segregated units even as late as the post World War II era. While FDR may have instituted the entitlements of which you speak ...it was the Clinton administration that put limitations on welfare to make it less than a life time entitlement. It was LBJ that appointed Thurgood Marshall to the bench of the U. S. Supreme Court as its first Afro-American justice. Marshall was probably one of the most brilliant lawyers and jurists of our time. He argued for one of the appellants in Brown v. Board of Education, 347 U. S. 483 (1954). Interestingly Justice Hugo Black (with whom you find fault) was one of the justices that heard argument in the case and participated in the unanimous decision to strike down segregation and the "Separate But Equal" doctrine. It was also LBJ that signed into law the Civil Rights Act of l964 and the Voting Rights Act of 1965.

The fact remains that racism was the status quo in the southern states and to a somewhat lesser extent in the northern states under the administrations of both political parties since the end of the Civil War. The voting histories you cite were a function of the culture that produced the politician and the constituency which he served. It was not a function of party affiliation. Civil rights were allowed to languish in limbo for almost a century under the administrations of both parties. The point is that membership in one party does not make one a racist anymore than membership in the other party makes him less of a racist.