It may be hard to justify a <i>national</i> high speed rail network, but the coasts easily have enough population density to make it work on a regional basis.<p>The big problem with rail in the US, at this point, is you&#x27;d have to build out an enormous number of track miles to make the system actually work for people who wanted to use it, and that&#x27;s going to cost a lot of money and displace a lot of people.