I’ve seen the $4B number tossed about, but I doubt its accuracy.
There were about 4M slaves, and $4B would require an average price of $1000. My understanding is that is more than a little high, so I use $750 instead.
Here’s a really interesting article about slave prices. It points out that comparing prices from one period to another is intrinsically challenging, but using three possible ways of doing so, the $500 average price of a slave in 1850 equates to somewhere between $11,000 and $162,000 today.
http://www.measuringworth.com/slavery.php
I don’t think people realize what happened in the South when the slaves were freed. The South had been investing its capital into slaves for many decades, and all of that capital - as capital - suddenly disappeared. Couldn’t be used as collateral for a loan or any other purpose.
So while the productive capacity of the region, deducting of course for the immense physical damage caused by the war, was perhaps theoretically higher, decades of capital accumulation had disappeared.
Think of the financial pain caused by the slight decline in wealth caused by our recent housing bubble burst. I have seen figures of perhaps 5% loss in national wealth, much higher of course for many individuals.
When the slaves were freed, the South lost perhaps 1/3 or more of its prewar capital.
In Huston's book, "Calculating the Value of the Union", his table 2.3 (page 28) lists 1860 census results for values of various categories of property, and "property", ahem.
These numbers are for the entire Union:
Sherman Logan: "the $500 average price of a slave in 1850 equates to somewhere between $11,000 and $162,000 today."
In overall economic terms, it's more than that.
For real apples-to-apples comparisons, I think you need to look at their "relative share of GDP" number, which corresponds to "how much national effort went into this project", and that number would today be $1,740,000.
So four million slaves then, at $500 per slave, corresponds to about $7 trillion dollars today -- a pretty hefty sum.
But the census total of $3 billion suggests an average cost of $750 and equates to more than $10 trillion today.
Finally, we should note again that $3 billion in slaves was more than the value of all Southern lands themselves, and more than the total Northern investment in railroads and manufacturing.
So the potential loss of such value through some actions in Washington DC, was certainly a matter of utmost concern, not just to large slave holders themselves (relatively few), but to every Southerner whose prosperity depended on their "peculiar institution".
Again, the capital that constituted slave workers was not lost. The ownership of the capital was lost. The banks would have had to loan the money to the black agricultural worker, or to a corporation that had an employment contract with him.
That a bank didn’t want to make a loan didn’t mean that they couldn’t have.