[scott00]

Why does the Jones act discourage trade between PR and the Caribbean? My understanding is it mandates use of US ships for shipping between US ports. It should therefore have no effect on shipping between PR and the various non-US Caribbean nations.

[gasbag]

The act says that anytime a non-US ship carries goods that are from a US port, including Puerto Rico, it cannot take those goods to any other US port. So instead of being able to do a sequence of [Barbados, Puerto Rico, Florida, Barbados], a ship would have to instead follow [Barbados, Puerto Rico, Barbados, Florida, Barbados]. It doesn't eliminate trade entirely, but it definitely increases costs--especially in PR itself, which has to rely only on US ships for US goods, creating a monopoly.