Electrification

One minor correction. The president of the New Haven was named Mellen, not Mellon. He was an experienced railroad manager who was basically one of J. P. Morgan's agents.
He is no relation to Andrew Mellon, the Pittsburgh oil and banking magnate.

The electrification of freight service in Boston was seriously under consideration as late as 1943. I have copies of drawings and correspondence from Westinghouse concerning the proposed catenary structure and how it would be insulated from some very low bridges in South Boston. One requirement would have been an oval shaped contact wire one inch tall that was to have been strung without a messenger.

High Voltage AC tends to lose less of its current in transmission over the catenary than DC. Like wind resistence or the friction of water going thru a pipe electricity loses some of its force flowing through wires. The loss per mile is less for AC than DC.

Actually, losses are mostly the same for DC or AC. The difference is DC systems tend to be much lower voltage.

DC is used in places at high voltages (more than 400kv) for electric transmission. In the northeast, there area number of HVDC links, out west, there's the Pacific Intertie, a MAJOR DC link.