US gave up on passenger train service for car/highway culture in the 50s/60s. At this point, trains work for short distance city center to city center (NorthEast Corridor is a good example) but not profitable or wise in rural freight locations as trains are often delayed/slow. The most profitable Amtrak routes are 4 hrs or less trips so investing in sleeper cars which can't financially compete with LCC air and significantly slower service wouldn't make sense.
I give you an example of a trip that would make a good overnight (leave evening and arrive AM) - NYC to Montreal via train takes 10-11 hrs with a cost of $70-150. Flying would take 1+ hrs (cost a bit more plus far away from city center on both ends). Driving would take 6 hrs. Bus takes 7-8 hrs and cheaper vs. train.
The train is ideal for those with stops in between the two major cities but anyone else with a care about time would prefer alternate methods.
I think one of hte longest routes is New Orleans to LA which it constantly late and I believe loses money due to delays and limited passengers. Just not profitable or able to compete with air or car culture.