I was a little taken by the state of American trains if this was true. Two days would mean at least 36h for me and that in turn would mean that the trains would have an average speed of 20mph.

But it turns out that it takes 20h, so twice that speed. Still not fast but better. With that duration it also seems unlikely that the speed is kept artificially low to allow some sleep on the train, as is very common in Europe.