[2 Kool 2 Be 4-Gotten]

From a pure territory point of view it looks like slavery is on the ascendancy but if you had a map that depicted RR track miles (as a proxy for industrialization) a different picture would likely emerge.

[BroJoeK]

"...if you had a map that depicted RR track miles (as a proxy for industrialization) a different picture would likely emerge."

The South was not as backward in 1856 as sometimes asserted, indeed, it's been said (though I can't confirm) that, on average, Southerners lived closer to railroads than Northerners.
Their problem, of course, was they had little industrial infrastructure to build & maintain railroads, depending on their cotton exports to pay for everything.
Similar, we might say, to some oil-rich countries today.