What is Merchant Marine Act Of 1920?

Legal Definition
The Merchant Marine Act of 1920 (P.L. 66-261), also known as the Jones Act, is a United States federal statute that provides for the promotion and maintenance of the American merchant marine. Among other purposes, the law regulates maritime commerce in U.S. waters and between U.S. ports. Section 27 of the Jones Act deals with cabotage and requires that all goods transported by water between U.S. ports be carried on U.S.-flag ships, constructed in the United States, owned by U.S. citizens, and crewed by U.S. citizens and U.S. permanent residents. The act was introduced by Senator Wesley Jones.

Laws similar to the Jones Act date to the early days of the nation. In the First Congress, on September 1, 1789, Congress enacted Chapter XI, “An Act for Registering and Clearing Vessels, Regulating the Coasting Trade, and for other purposes”, which limited domestic trades to American ships meeting certain requirements.

The Merchant Marine Act of 1920 has been revised a number of times; the most recent revision in 2006 included recodification in the U.S. Code. In early 2015 Senator John McCain filed for an amendment that would essentially annul the Act.

The Jones Act is not to be confused with the Death on the High Seas Act, another United States maritime law that does not apply to coastal and in-land navigable waters.
-- Wikipedia