All 3 of these "railroads"still exist "on paper". In fact,some NO Tresspass signs along Freight Mainline,in S.Maine & N.H. are signed "Boston & Maine Corp",despite being put up 2-3 years ago.Probably a lawyer or accountant can figure it out,if they could see an organizational chart of Guilford Transportation Industries! Because we have that broken up into G.Rail Systems,Pan-AM(note they have(or had?)the subsidiary commuter line using the old Boston-Maine Airways!)Aroostook & Bangor Company(ties) etc. Then under Guilford Rail Systems,the 3 that you mentioned. Some phone books,still have the "Guilford" numbers under B&M,or MEC or ST! Gotta be a tax savings,or a legal reason for doing this,but its NOT always done. When Emmons(now G&W)bought the old Grand Trunk from CN in 1989,ALL vestiges of GT/CN names vanished. Maybe it has to do with "registration" & licensing of the locomotives. When I worked part-time for Hertz Rent-a-Car,in the 60's & 70's,the Portland,Maine corporate office controlled most agencies in N.H. & Vt.,and we had to register a certain % of our car fleet in those 2 states. So,I would take the "paperwork" & a blank check to the nearest registery in N.H. or Vt. from Maine. Thats when I found out just how much cheaper N.H. was to register a car in than Maine.like 1/2 for some 1966 Galaxies! Bud