Slavery was not an inevitable means of launching the US economy. Even though it may have jump started the economy at first, when slavery ended, it sent the economy into shambles and ruined it for a very long time. Farming was not the key to the economy's success, it was manufacturing, which slavery did not cause.
...evolved without the need for institutional society. While affordable labor is necessary, keeping that labor in chains generation after generation is one of the most disgusting chapters in our nations history, and a chapter that was not necessary to our nations success. After the civil war, slavery was outlawed but production from southern agriculture rebounded in spades.