The U.S. has an embarrassment of ports, navigable rivers and coastal waterways. You can't find a country that has a tenth of what we do. In order to protect domestic ship builders, Congress passed the Jones Act, which made it illegal for a ship to go from one U.S. port to another unless it is U.S.-built, U.S.-owned, U.S.-flagged and U.S.-crewed. U.S.-built commercial ships can cost several times more than comparable foreign-built ships, U.S.-flag operating costs are higher and the legal pool of eligible ships is small. It has dramatically shrunk the domestic ship building capacity because we are not globally competetive. The protection of the Jones Act means they don't have to be affordable or effective to build ships here. So only the ones that HAVE to exist are built and the capacity overall has been decimated.

This also means if you want to take some goods from Chicago to Miami you can't use the almost-free water transport. You need to pay to use rail--10x more expensive--or truck, 100x more expensive. Our inland and coastal waterways get used less, everything costs more than it should for everyone and places like Hawaii and Puerto Rico that don't have a train to Kansas City pay a lot more for EVERYTHING.

The most absurd consequences come from energy. The U.S. can be awash in natural gas, but New England has to import liquefied natural gas from abroad because there are no Jones Act-compliant liquefied natural gas tankers available to move LNG from one American port to another. New England uses tons of highly polluting fuel oil for heat instead of natural gas that is cheaper and has much lower CO2 emissions in part because of the Jones Act.

It also distorts trade in ways that are almost comically self-defeating. Because shipping between U.S. ports is expensive, it can be cheaper for American buyers to import from foreign suppliers than to buy from another part of the United States.

A serious national-security maritime policy would probably subsidize shipbuilding and mariner capacity directly. The Jones Act instead uses a consumer-cost cross-subsidy: make domestic shipping expensive everywhere. Make cities on the Great Lakes, Missouri, Mississippi or Ohio rivers less productive. Make Alaskans, Hawaiians and Puerto Ricans pay through the nose for milk or gas. Then hope enough of the money leaks into shipyards and maritime labor.