Consider the fact that Trump last week was forced to waive the century-old Jones Act, which stipulates that only US-built and flagged ships can carry goods between American ports. It’s been a contentious piece of legislation for a long time now, since the loss of the US industrial base in shipping has diminished economies of scale in American shipbuilding. That has meant that many foreign builders can manufacture ships and run maritime operations more cheaply than the US industry can. Trump hopes to bring down oil and gas prices at least temporarily by allowing foreign vessels to ship goods between American ports, thus making the shipping of such commodities — which have risen sharply in price due to the Iran war — cheaper.