The Merchant Marine Act and The Jones Act
The Merchant Marine Act of 1920
On June 5, 1920 The Merchant Marine Act (MMA) was passed by the 66th United States Congress and signed into law by President Woodrow Wilson. While this law covers a wide array of topics, it primarily addresses what is most commonly referred to as cabotage. For purposes of The MMA, cabotage is essentially the transportation of people or goods within U.S. waters and between two U.S. ports. While in modern times this term applies to transport via road, air, rail, and waterways, it originated from the French word caboter, which means to travel by the coast, and applied initially only to transport via waterways.
Section 27 of The Merchant Marine Act of 1920

Senator Wesley Jones (R-WA) was the original Congressman to propose Section 27 of The MMA, more commonly known as The Jones Act. In addition to various areas regulating a seaman's rights while operating in a commercial trade environment, The Jones Act also addresses transportation of goods via water between U.S. ports and requires them to take place on U.S.-flagged vessels built in the United States, owned by U.S. citizens, and operated by U.S. citizens or permanent U.S. residents. While the law was originally intended to support and protect the U.S. cargo ship building, transportation and maintenance industries, the law applies today to ALL foreign-built vessels, including those used for recreational purposes.
The Ultimate Purpose of The Merchant Marine Act of 1920
In modern times pundits and politicians alike have interpreted and argued the true purpose of the law, however the preamble doesn't leave much to argue. As you read through the preamble below keep in mind current events taking place at the time. Most notably the Treaty of Versailles had just been signed in 1919, signaling the end to World War I. In addition 65,000 laborers participated in The Seattle General Strike of 1919, which had its infancy in labor wages and working conditions associated with World War I manufacturing. It's no coincidence that Section 27 was also proposed by a Senator from Washington, where the strike took place. In addition the country was at a peak in terms of protecting its national interests, labor market, and that of the American people in general.