Because the American people where scared that if they gave people that much power over them, like there would be in a strong central government, then the same tyranny that happened with King George and Great Britain, would happen again in their own government.
The Boston Port was closed dues to... I think a Boston Tea Party.
9/11 happened because Osama Bin Laden wanted to declare a holy war against the United States. He also wanted to retaliate against America for its aggression towards muslims.
Slavery it wasn't needed for west expansion