Show us any data that shows that wage labor was displacing slave labor. In fact, the opposite was happening in the upper south. As demand for farm labor decreased, crafts and manufacturing were slowly moving from wage labor artisans to slaves rented from their rural owners. From craft labor like blacksmiths to shoemakers to common laborers in factories, mines, mills and railroad construction, rented slave labor was in fact replacing wage labor in the upper south. In the lower south, the "opportunity costs" of taking slaves away from the cotton fields was suficiently high that wage labor was less expensive than the price owners would demand for the use of their slaves. That opportunity cost premium is a very far way from wage labor being cheeper than slave labor.
You also highly exaggerate to costs of slave owning. While initial purchase was indeed expensive, estimates of costs of upkeep averaged between $2 and $3 per year per slave. Unless house slaves of a prosperous owner, they only had hand-me down clothing. Food was mostly what the slaves could grow in their "off-hours" with what ever reject scraps of meat the white family didn't want. (Would anyone invent something like chitlens if they had access to a rump roast?) Housing was dirt-floor shacks containing multiple "families". Medical care was spotty at best. There were no educational costs, no luxuries, no entertainment expenses.
The immigration trends for one. Circa 1857 immigration into the southern states, which had been relatively stagnant for a couple decades, began to increase. The economics of immigration dictate that labor moves where opportunity for obtaining wealth exists for the reason that immigrants are utility maximizers (meaning they go where they think they can get a job or make money). The presence of wage jobs accordingly tends to induce immigration to the location of those jobs.
In fact, the opposite was happening in the upper south.
Actually it was the Virginia where the immigration trends most noticeably reversed in the 1850's. Virginia is the largest upper south state, so that appears to contradict your theory.
As demand for farm labor decreased, crafts and manufacturing were slowly moving from wage labor artisans to slaves rented from their rural owners.
Wrong. Skilled labor and craftsmen among the slave population had been commonplace since the mid-1700's when indentured servant artisans took on slaves as apprentices upon their arrival here. All the major plantation houses of architectural significance today from Mount Vernon and Monticello to the lesser known ones on the James River and Potomac had long employed this system. By 1850 it was not replacing farm labor for the reason that craft labor itself was on an even greater economic decline than farm labor due to increased mechanization in the production of former craft goods. It is this same reason why we still have farmers today but we don't have any blacksmiths, exempting of course those wierdos who work at renaissance fairs.
From craft labor like blacksmiths to shoemakers to common laborers in factories, mines, mills and railroad construction, rented slave labor was in fact replacing wage labor in the upper south.
No it wasn't. Craft labor as a whole was on the decline faster than any unskilled labor position. Slave labor had always been used in unskilled construction projects like railroads and buildings.
You also highly exaggerate to costs of slave owning. While initial purchase was indeed expensive, estimates of costs of upkeep averaged between $2 and $3 per year per slave.
Provide your source on that and a breakdown of the costs as well. I ask because it is doubtful they account for non-dollar expenses such as those that may be obtained from the farm itself (i.e. food, which can come from the grown produce of a plantation's domestic garden). You should also note that the seemingly small ammount of 2-3 dollars is the equivalent of about 50 dollars today - still not much, but a heck of a lot more than the tiny $2 per person fee. Multiply that $50 cost by 100-150 slaves and pretty soon you are talking a substantial ammount of money.
Unless house slaves of a prosperous owner, they only had hand-me down clothing.
Even hand-me downs cost something initially and have some value of their own. That aside, much of the slave clothing was NOT hand-me down but rather self-produced by the same slaves who sewed the clothing for the plantation household.
Food was mostly what the slaves could grow in their "off-hours" with what ever reject scraps of meat the white family didn't want. (Would anyone invent something like chitlens if they had access to a rump roast?)
The so-called chitlins, or chitterlings "delicacy," is largely the product of poverty during the post-war economic climate among the black communities. They were the only scraps that they could afford. Food on plantations before the war consisted primarily of the products obtained from the domestic gardens. In this sense many large plantations were like micro-cities that sustained their own populations on what they grew.
Housing was dirt-floor shacks containing multiple "families".
Indeed they were, yet housing still costs something. It should be similarly noted that those shacks were not of substantial difference in quality from the dwellings of most of the working class in that era, be they tenements in the big cities or single room dirt floor cabins in the woods.
Medical care was spotty at best.
Medical care from the era was spotty at best in its entirity for simple lack of knowledge. The assertion that slaves, in most cases, were not provided with what was available defies economic sense because of the investment factor (for example, are you going to deny a slave that cost 100 dollars a dollar's worth of medicine for an illness that prevents him from working or, worse, kills him when untreated?)