When the US was founded, half of the states were slavers, the other half free. Guess which half prospered? The free North! Which stagnated? The slave South.
Did you know that the Slave South was unable to supply their troops? They were largely barefoot. The reason they were in Pennsylvania was to raid a shoe factory (but got smashed at Gettysburg instead). Towns and cities and industry sprouted up all over in the free North, not so much in the South.
The Civil War resulted in burning the South to the ground. Poof!
As for natural resources, why is resource-rich S. America mired in poverty? Why did the Indian nations never industrialize, and remained poor? Why did resource-poor Japan become super rich after being burned to the ground in WW2? Why did resource-rich Russia never become prosperous? Why did zero-resource Taiwan become a wealthy powerhouse? Why is resource rich Africa still stuck in poverty?
There is no connection between resource rich and prosperity.