At the start of the First World War,
the American merchant marine, which up until the American Civil War transported most American goods,
represented only 8% of the world fleet, behind that of Germany at 11% and the United Kingdom, which held more than half of all oceanic tonnage. When the war was declared, German ships sought refuge and ships of the Allied nations were prioritized to support the total war effort of the Entente.
The United States was at the mercy of foreign shipping. The response was the Shipping Act of 1916 which aimed to create a merchant marine to meet the requirements of the commerce of the United States. To accomplish this, the United States established the U.S. Shipping Board to fill the void left from foreign merchant marines and the United States domestic fleet could not handle. When American shipping was directly challenged by German submarines, the Emergency Fleet Corporation was incorporated to oversee a massive shipbuilding program that resulted in the construction of over 2,000 ships.
At the end of the First World War, the US Shipping Board and Emergency Fleet Corporation were left with this large fleet and the aim to get these ships in the hands of private American companies, establish an American presence on key essential trade routes, and ensure that the domestic transportation of goods was not in the hands of foreign shipping that could be diverted. The result was the Merchant Marine Act of 1920, or more commonly referred to as the Jones Act for its author Republican Senator Wesley Jones of Washington.