There is a world of difference between "conscription practices, naval military recruiting practices, and industrial labor practices" (all of which also inflicted on the descendants of slaves) and actual laws on the books based explicitly on race and ancestry.
Were the descendants of serf banned from voting? Were the descendants of serfs banned from buying property? Did the descendants of serfs have to use separate drinking fountains? Were the descendants of serfs lynched by hooded mobs? These were substantial discriminations still taking place one hundred years after slavery.
Five is a sufficiently close approximation to infinity. -- Robert Firth "One, two, five." -- Monty Python and the Holy Grail