The U.S. has 9 such metro areas. NYC, LA, Chicago, Dallas, Houston, Washington DC, Miami, Philadelphia, and Atlanta. You could profitably run high-speed rail

The U.S. has 9 such metro areas. NYC, LA, Chicago, Dallas, Houston, Washington DC, Miami, Philadelphia, and Atlanta. You could profitably run high-speed rail between NYC and DC, hitting Philadelphia on the way. Amtrak does run a sort of high speed service on this route. There's a study underway for a privately funded high-speed rail connecting Dallas and Houston. Miami to Atlanta is at the edge of what might make sense. Sizable metro areas can decline, Detroit is now 1/3 the size that it was at its peak in the 1960s. The railway station was abandoned. https://ebow.org/artwork/470141-The-Great-Hall.html https://ebow.org/artwork/470141-The-Great-Hall.html