The severing of the economies at the outset of the Civil War, and the total destruction of the southern economy during the war, yet the continued prosperity of the northern economy shows that the northern economy was not dependent on slaves.
> The North did originally have some enslaved people.
Yes, and the ending of that did not retard the economy or reduce the middle class in any detectable way. The middle class increased throughout the 19th century.
Slavery was integral to the entire U.S. economy, but that economy was changing in the mid-19th century, and indeed it's not totally false that those economic changes were part of what led to the civil war.
// Capitalists in the North profited by investing in banks that handled the exchange of money for people, or in insurance companies that provided insurance for the owners’ investments in enslaved people. So did foreign investors in Southern securities, some of which were issued on mortgaged slaves. The hotbed of American abolitionism — New England — was also the home of America’s cotton textile industry, which grew rich on the backs of the enslaved people forced to pick cotton. The story of America’s domestic slave trade is not just a story about Richmond or New Orleans, but about America. //
"“In the decades between the American Revolution and the Civil War, slavery—as a source of the cotton that fed Rhode Island’s mills, as a source of the wealth that filled New York’s banks, as a source of the markets that inspired Massachusetts manufacturers—proved indispensable to national economic development,” Beckert and Rockman write in the introduction to the book. “… Cotton offered a reason for entrepreneurs and inventors to build manufactories in such places as Lowell, Pawtucket, and Paterson, thereby connecting New England’s Industrial Revolution to the advancing plantation frontier of the Deep South. And financing cotton growing, as well as marketing and transporting the crop, was a source of great wealth for the nation’s merchants and banks.”"
> The North did originally have some enslaved people.
Yes, and the ending of that did not retard the economy or reduce the middle class in any detectable way. The middle class increased throughout the 19th century.