That is about 280 miles, so at 1:32 scale that would be about 8-3/4 miles of gauge 1 track, a rather outlandish amount!
It is not uncommon to model distances at 1 or 2 percent of the total (i.e.: if it is 100 miles from one town to another, you model only 1 or 2 miles of it, leaving out repititious or dull scenery) at that rate then you need between 462 to 924-feet of track for the 280 miles at 1:32 scale. This is within the realm or reality, but still would make for a very large layout. It would not have to be all in one straight line, but could be a zigzag with one city in one corner of the area and the other city at the diagonally opposite corner and however many "S" curve zigs as needed to account for the distance.
Depending on which city you find most fascinating you could easily start at that one and do the first few miles and see how it goes... if all is well, then keep adding miles until the whole thing is done. (Not unlike the way the real RRs did it!)