The Boston Port Act was the act that shut down Boston harbor and hurt the economy of the colonies. No ship was allowed to enter or leave until the colonists paid for the tea that had been destroyed.
Ths act was part of the Intolerable Acts signed by the Parliament of Great Britain in 1774 to punish the inhabitants of Boston for the incidents that would become known as the Boston Tea Party.
A side effect of this act was the strenghthen of the anti-British feeling.