My question relates to the following quote from chapter XI of the Narrative of the Life of Frederick Douglass:
I had very strangely supposed, while in slavery, that few of the comforts, and scarcely any of the luxuries, of life were enjoyed at the north, compared with what were enjoyed by the slaveholders of the south. I probably came to this conclusion from the fact that northern people owned no slaves. I supposed that they were about upon a level with the non-slaveholding population of the south. I knew they were exceedingly poor, and I had been accustomed to regard their poverty as the necessary consequence of their being non-slaveholders. I had somehow imbibed the opinion that, in the absence of slaves, there could be no wealth, and very little refinement. And upon coming to the north, I expected to meet with a rough, hard-handed, and uncultivated population, living in the most Spartan-like simplicity, knowing nothing of the ease, luxury, pomp, and grandeur of southern slaveholders. Such being my conjectures, any one acquainted with the appearance of New Bedford may very readily infer how palpably I must have seen my mistake...
Here I found myself surrounded with the strongest proofs of wealth... From the wharves I strolled around and over the town, gazing with wonder and admiration at the splendid churches, beautiful dwellings, and finely-cultivated gardens; evincing an amount of wealth, comfort, taste, and refinement, such as I had never seen in any part of slaveholding Maryland.
...But the most astonishing as well as the most interesting thing to me was the condition of the colored people, a great many of whom, like myself, had escaped thither as a refuge from the hunters of men. I found many, who had not been seven years out of their chains, living in finer houses, and evidently enjoying more of the comforts of life, than the average of slaveholders in Maryland. I will venture to assert, that my friend Mr. Nathan Johnson... lived in a neater house; dined at a better table; took, paid for, and read, more newspapers; better understood the moral, religious, and political character of the nation,—than nine tenths of the slaveholders in Talbot county Maryland. Yet Mr. Johnson was a working man. His hands were hardened by toil, and not his alone, but those also of Mrs. Johnson.
Are there other historical data that back up or contradict Douglass's observations? For example, did tradesmen in the urban northeast commonly live in greater material comfort than slaveholding plantation owners in the south? Are there records about wealth distribution and stratification in slaveholding vs free states at this time?