The socio-economic classes of the Old South:
The most numerous group of people in the Old South was the yeoman farm families. Yeomen are farmers who own their own land and do their own work, or if they have hands, they work along side their hands. Many of them were almost poor; some were wealthier than some planters.
The second most numerous group was the slaves; slaves varied in social class according to whether they were household servants or field hands. They also varied in economic level: Some masters paid bonuses for good work while others administered whippings for bad work; some masters furnished good housing while others furnished shacks; some masters allowed slaves to raise and sell garden truck while others did not. Most slaves lived on small plantations or with yeoman farm families. Plantations with hundreds of slaves were rare.
The upper class of the Old South mostly consisted of wealthy planters and wealthy merchants; most planters and most merchants were not wealthy.
The middle class consisted of planters, yeoman farmers, merchants, preachers, lawyers, doctors, and mechanics.
The lower class included poor whites. Most poor whites were either laborers doing the same work as slaves or were tenant farmers. There was a social division amongst this poorest of economic levels–not all poor whites were trashy but some were. Most slaves, especially household servants, considered themselves better than poor whites, and most were.
There were also free blacks. Some in Virginia and Maryland had always been free because the first blacks brought to America were held only as indentured servants for a few years, then released from their bondage. Many free blacks were in Louisiana where it was common for white masters to mate with black slaves, then to free their children and give them some estate for their support. Many states had laws making life hard for free blacks in order to make freedom unappealing to slaves. Free blacks fell into all economic classes including laborers, tenant farmers, yeoman farmers, mechanics, and planters. (I know of only one Old South era black doctor, he was in North Carolina.) There were many black preachers, both slave and free; probably no black lawyers.
Most mechanic-work in the Old South (carpentry, brick-laying, black-smithing, etc.) was performed by slaves so that the Old South had a smaller class of free, white mechanics than the North.
Historians consider a farmer who owned 20 or more slaves to be of the planter class, while farmers owning fewer than 20 slaves were of the yeoman class. Most yeomen owned no slaves.
Plantations were farms devoted mostly to one cash crop. Plantation crops included tobacco, cotton, rice, sugar, hemp, longleaf pine (naval stores).
Mountainous regions and regions of poor soils were devoted to livestock farming. Some livestock farmers were wealthier than some planters.
Social Relations in Our Southern States
by Daniel Hundley, can be found on the Internet. It was published about 1860 and tells a lot about the various classes of people.
Typically, Old South refers to the antebellum period in America's history. During that time the social class divisions were basically as follows:
- Gentry (or planter class): white plantation owners and slaveholders of more than 20 slaves; high class officials; professionals such as doctors and lawyers; a very small percentage of the population but held most of the political positons so very influential.
- Middle class: slave owning whites - smaller business men and merchants; held lower official positions or were professionals of a more moderate income.
- yeoman farmer/skilled labor class: smaller land owners who farmed their own land independently; not slave owners; used their land, livestock and produce for personal use.
- poor whites: non-land owners; day laborers; went from job to job; mostly illiterate
- free black people (not necessarily in all states): non-slaves but also poor due to prejudice, lack of equality, and hatred; some were skilled laborers, some were literate, a few even owned slaves themselves
I assume that you are referring to the American South in the days before the Civil War.
In that time and place, the major classes were the elites who owned many slaves, the "middle class" who owned only a few slaves, and the much larger lower classes who owned no slaves at all and who were usually quite poor. This leaves out, of course, the slaves and the relatively small number of free blacks.
The large planters were the top of the pyramid both economically and socially. They were the only truly rich people in the South and they tended to dominate the society. They occupied positions of leadership and they generally were what everyone else wanted to be.
The middle class generally strived to reach the level of the higher elites. They sometimes would work for those elites as, for example, overseers. They might also be economically dependent on them. The lower classes were only a very short way above the slaves economically. Socially, however, they were of course free and had the rights that all whites did.