Whatever cottons importance to export market (which wasn't particularlly large anyway for US at this time?), slavery was nevertheless very important, as the value of the slaves ca 1860 constituted more than ⅓ of the total wealth of the entire country!? and more than ½ of the wealth of the Southern states. Whatever the reason for that value, that value was real and the prospect of having the value TAKEN from the South was enough of an incentive to cause them to fight very, very hard, if w/o success, to keep that loss from happening.
No, slavery was not important to the United States of America macroeconomics, but it was important to the southern microeconomics, there is a difference you know? How in the world did slaves account for 1/3 of the total wealth in the United States when there were slaves only in the southeast and nowhere else, and the value of the slave was not calculated in the national GDP?
The value of a slave was not real value even in the south, but nominal only. Furthermore, slaves were sold and transferred only in the south. Are you saying that once a slave owner sold a slave he or she gave the government the money? Was there a excise tax on slaves when they were sold? I doubt it, but if that were the case it still would not remotely add up to 1/3 of government wealth.
From a classical economic standpoint slaves would not be considered real wealth for a couple of reason(s). First, the slave's value fluctuated in boom and bust cycles that was/is common for a commodity like cotton. In other words, the slave's 1860 value was a result of cotton being in a boom cycle from 1830-1860, but that value would not have held its 1860 worth in a bust cycle. The four decades prior to the CW cotton was in boom cycle, which the demand for it increased every decade and the demand for labor increased along with it. The demand for cotton and the demand for slaves ran parallel, and the value of a cotton slave ran parallel with cotton production. The more cotton that was produced the more value of a slave increased. Conversely, the less amount of cotton production the decrease in the slave's value. That 1860 value never would have stood the test of time in the subsequent cotton bust in the second half of the 1800s. It don't matter anyway, that's because the slave did not hold its value outside the south, period.
The problem is that economists run into is that emancipation hindered a quantitative analysis on the value of the slave during a bust cycle that occurred during the four decades following the CW. Nevertheless, paradigms of cotton demand can easily determine that the slave's value was not remotely as high in a bust cycle than boom cycle. Therefore, the slave was a volatile asset because there were variables that fluctuated the value of a slave, which means it was a risky investment. Moreover, the slave was a non-liquid asset that could not be easily converted to cash. Who was going to buy the slaves at their 1860 value? Assure you nobody outside the south would have bought them, therefore, the slave was an White Elephant investment. Therefore, we can take that $3-4 billion value for slaves with a grain of salt, it was nominal only.
Furthermore, cotton production value has been exaggerated also from the sect of economic historians that double and triple intermediates, even though they have done it—it was an economic impossibility. That type of accounting error has sored cotton's economic value beyond the scope of the actual GDP. Never happened. People think that because cotton exports made up of 80% of the total exports that it was a huge number. No, the reason why it wasn't a big number was because the USA was closed economy and most of the USA GDP stemmed from manufacturing, transportation, banking and food stuff agriculture. The 80% of exports and tricky, because it did make up the majority of exports but it actually was only 5% of the nation's GDP. If we argue that the value of a slave ran parallel with cotton production it still would not exceed the 5% of the GDP, which is not remotely 1/3 of the wealth of the USA.
Slavery was not valuable outside the south. Prove how slaves were valuable to the rest of the USA. Prove how the slave's value was 1/3 of the wealth in the USA.