Here is Fred Law Olmsted thought on slavery... from wiki... A one-volume abridgment, Journeys and Explorations in the Cotton Kingdom (1861), was published during the first six months of the American Civil War at the suggestion of Olmsted's English publisher. To this he wrote a new introduction (on "The Present Crisis") in which he stated explicitly his views on the effect of slavery on the economy and social conditions of the southern states. My own observation of the real condition of the people of our Slave States, gave me ... an impression that the cotton monopoly in some way did them more harm than good; and although the written narration of what I saw was not intended to set this forth, upon reviewing it for the present publication, I find the impression has become a conviction. He argued that slavery had made the slave states inefficient (a set amount of work took 4 times as long in Virginia as in the North) and backward both economically and socially. The profits of slavery fell to no more than 8,000 owners of large plantations; a somewhat larger group had about the standard of living of a New York City policeman, but the proportion of the free white men who were as well-off as a Northern working man was small. Slavery meant that 'the proportion of men improving their condition was much less than in any Northern community; and that the natural resources of the land were strangely unused, or were used with poor economy.' Southern civilization was restricted to the wealthy plantation owners; the poverty of the rest of the Southern white population prevented the development of civil amenities taken for granted in the North, he said. The citizens of the cotton States, as a whole, are poor. They work little, and that little, badly; they earn little, they sell little; they buy little, and they have little – very little – of the common comforts and consolations of civilized life. Their destitution is not material only; it is intellectual and it is moral ... They were neither generous nor hospitable and their talk was not that of evenly courageous men.