The Framers chose federalism rather than having a unitary system (all power given to the central government) because people did not trust central government.
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Answer:
The reason was that the tensions, and the subsequent victory of the Union Side in the Civil War allowed the government of Abraham Lincoln to end slavery in the United States.
In other words, he had enough political capital because he had the backing of both union politicians and the people due to the need of leading the war against the Confederate Side in the Civil War.
Europe's System of Military Alliances
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