Just piggybacking on Dr. Gutzman, George Mason at the Phil. Convention in 1787 advocated a 2/3 majority for any potential “navigation” legislation because he understood that these laws would mainly hurt the South while benefiting the North. Everyone knew that the two sections were different even at the time of the War for Independence. That is why the Union was constructed for “general purposes” only. Under this idea, the South and the North would be free from the meddling of the other section.