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https://en.wikipedia.org/wiki/United_States_Merchant_Marine
The United States Merchant Marine are United States civilian mariners and a fleet of U.S. civilian and federally owned merchant vessels. These fleets are managed by either the government or private sector, and engage in commerce or transportation of goods and services in and out of the navigable waters of the United States. The Merchant Marine is responsible for transporting cargo and passengers during peacetime. In time of war, the Merchant Marine can be an auxiliary to the Navy, and can be called upon to deliver military personnel and materiel for the military.