> Rail is not cheap. It's feasible when we have population density. It would make sense along the DC-Boston megalopolis and perhaps SF-San Diego, maybe some stretch of Texas. It makes little sense in the rest of the country.

As part of its HSR strategic plan, back in '09 the Obama admin identified over half a dozen regions well within HSR densities and distances (the existing north-east corridor, nothern new england linking to canada, southeast along the coast, the chicago area, the gulf coast, south-east central though Texas, the californian coast and the pacific northwest).