Thanks for posting a most interesting chart.
I think it helps confirm what I quoted above.
As I read that chart, you have a string of low-price years in the 1840s, ending about 1850 after which prices doubled -- ie., from 5.8 in 1849 to 11.7 in 1852.
Sure cotton prices were occasionally higher earlier in the century, but not often, and those years were before wide-spread use of cotton gins, when production was orders-of-magnitude lower.
Further more, those earlier prices were irrelevant in the 1850s, because what mattered then was all the cotton plantations which survived the low-priced 1840s were positioned to prosper mightily in the higher-priced 1850s.
And that's the whole point being made here: during the 1850s, with greatly expanded land under cultivation (1/3 more) and higher cotton prices (nearly doubled), total US cotton production rose from $74 million in the 1840s to over $207 million (tripled) in 1860.
Meanwhile, inflation rose just 33% during the 1850s.
The result of this unprecedented prosperity was average slave prices rising from $925 in 1850 to $1,658 in 1860 (79% increase).
So, it seems to me this picture of Southern prosperity is consistent and long-term, during the 1850s.
What exactly is your problem with it?
This brings us to my humble opinion on how the Confederacy could have won their independence.
In 1861 there was yet another bumper crop of cotton -- at least $200 million worth -- sitting in rail cars and at docks from Galveston Texas to Norfolk, Virginia.
For reasons which defy logic, that $200 million worth of cotton never shipped, was never sold and so far as I know was lost to the Confederacy.
Had it been shipped, sold & banked, $200 million in 1861 would have purchased hundreds of thousands of repeating rifles, with ammunition (circa $100 each), plus the latest equipment to produce more, plus dozens of state-of the art war-ships ($500,000 each), field artillery, plus steel for rail & engines, copper for telegraph wires, etc., etc.
So right away, the Confederacy would start with a huge material / technological advantage.
Next, it required patience, patience and diplomacy -- take all those Fire Eating hot-heads and put them in political straight-jackets until the time is right.
Delay the start of war until the first blows can be overwhelming and decisive.
Wait, wait, wait... until the new Confederate army is equipped, trained, lead & supported logistically (railroads) like none ever seen before.
Under no circumstances pick a fight until you're certain you can win, and in the mean time be as nice, as diplomatic and legalistic as humanly possible.
Indeed, if you really wanted to win, don't ever start the war.
If you have $200 million in the bank in 1861, how much does your average Congressman cost in those days?
Why not just buy off a bunch, and get them to approve your secession, legally, constitutionally, peacefully?
US states with the highest cotton production in 2007: