BroJoeK,
If the census statistics are correct that ~40% of people in the southern states were slaves, and that was a fairly constant number from state to state, then there is a problem with your assertion that higher percentages of whites owned slaves in the deep south than the upper south.
The issue is that the very, very large plantations, held and run by single families were much more common in the deep south. These large plantations would have hundreds, even thousands of slaves. Pure math would then lead to the conclusion that you had fewer owners of larger numbers of slaves in the deep south and more owners of smaller numbers of slaves in the upper south.
In reference to your overall presumptions, IF your 6% figure is correct and only applied to heads of households, you still have to have an extremely large average family size to get to 50% of whites being in a slave holding family. If the average number of slaves held was only 2, then only 33% of white families could have owned slaves, before the supply was exhausted. And the average was a lot higher than 2.
Before you get too preachy, do the simple math.
I'm never "preachy", and I have done the math.
SampleMan: "If the census statistics are correct that ~40% of people in the southern states were slaves, and that was a fairly constant number from state to state..."
FRiend, those census numbers are readily available, and I even set up a little spreadsheet to calculate the percentages.
First, let me ask you this question: do you grasp the historical concept of "Deep South", versus "Upper South", versus "Border States"?
If you don't "get" that, then you know literally nothing -- zero, zip, nada -- about the Civil War.
So, do I need to explain it to you in great detail?
The first seven states to secede, circa January 1861, were the Deep South -- South Carolina west to Texas.
In those seven states, the percentage of slaves was over 50% in South Carolina and Mississippi, but only 30% in Texas.
Overall, in the original Confederacy, slaves made up 47% of the population.
In those Deep South states, the percentage of slave-owning families ranged from about 50% in South Carolina and Mississippi down to 30% in Louisiana and Texas.
The four Upper South states refused to secede, just because Lincoln's "Black Republicans" got elected in 1860.
But after the Deep South provoked, started and declared war on the United States, then Virginia, North Carolina, Tennessee and Arkansas felt compelled to join the Confederacy.
In the Upper South, the slave population ranged from 31% in Virginia to 26% in Arkansas, averaging 29% overall.
Their percentage of slave-owning households ranged from 28% in North Carolina to 20% in Arkansas, averaging 25%.
The four Border States (Delaware, Maryland, Kentucky, Missouri) refused to join the Confederacy, even after it declared war.
One reason is obvious: in those Border States, the slave population ranged from 20% in Kentucky down to just 2% in Delaware.
The percentage of slave-owning households ranged from 23% in Kentucky down to 3% in Delaware, averaging 16% overall.
The important point to remember here is that both the numbers of slaves and percentage of slave-owning families fell as you travelled from Deep South through Upper South to the Border States.
And that fact alone goes a long way towards explaining both why the Deep South started the Civil War, and why they eventually lost it.