Why did the Framers find it necessary to invent federalism at the Philadelphia Convention?
Also, the colonies were very different. The South features plantations, while in New England shipping and industry were stronger. Different regions had different religious beliefs. The New Englanders, descendents of the Puritans and Pilgrims, had strong Protestant roots, while Maryland had Catholics, Virginia Anglicans, and Pennsylvannia Quakers. Also, geography made it hard for quick communication and isolated different towns, necessitating self-government to deal with local crisises quickly. Thus, federalism was necessary because local needs were extremely different and could only be met by local governments. (But national government was necessary as well so the nation could be united against foreign threats.) So the founders used federalism to accomodate the needs and desires of various regions while simultanously producing a united nation.
