Okay.
Phoenix, Arizona (pop. 1,567,924)
Columbus, Ohio (pop. 1,773,120)
Las Vegas, Nevada (pop. 1,865,746)
Nashville, Tennessee (pop. 1,550,733)
Louisville, Kentucky (pop. 1,244,696)
Have a look at the Amtrak system map, it's barely a skeletal service compared to the density of lines...