[1][2][3][4][5] PTM's activities were vital to Portland's role as a winter seaport receiving Canadian products from the Grand Trunk Railway for export to Europe.

Shipping from Portland declined sharply as Canadian exports were routed via the Maritime ports of Saint John, New Brunswick and Halifax, Nova Scotia following nationalization of the Grand Trunk in 1923.

PTM was acquired by Guilford Transportation Industries in 1981,[6][7][8][9][10][11][12][13][14] and continues as CSX Corporation Portland occupies an Atlantic coast peninsula between Back Cove to the north and the Fore River estuary to the south.

Westbrook is inland of Portland where the pre-railroad Cumberland and Oxford Canal provided transportation for mills using water power of the Presumpscot River.

Grand Trunk Railway from Montreal entered Portland from the north via a long trestle over the mouth of Back Cove.

The Grand Trunk yard and wharves occupied the seaward end of the Portland Harbor waterfront along the north shore of the Fore River estuary.

[22] Maine Central Railroad Mountain Division from St. Johnsbury, Vermont entered Westbrook from the northwest paralleling the old canal along the Presumpscot River.

[8][12][23][24] Boston and Maine Railroad Worcester, Nashua and Portland Division from Rochester, New Hampshire entered Westbrook from the west.

Wharf 1 had water frontage of 1,000 feet (300 m) and included a 100,000-square-foot (9,300 m2) warehouse for handling package cargo interchanged with ships of up to 30-foot (9.1 m) draught.

[54][55][56][57][58][59] Yard 3 along the original Boston & Maine eastern route served the South Portland waterfront of the Fore River estuary including PTM Wharf 4, the New England Shipbuilding Corporation and the Portland-Montreal Pipe Line terminal.

Yard 7 was the interchange with the Grand Trunk Railway until the Portland Junction connection was severed during construction of a highway bridge over the mouth of Back Cove in 1947.

Wharf 3 had water frontage of 1,500 feet (460 m) designed for handling bulk commodities from ships and barges of up to 30-foot (9.1 m) draught.

The wharf included a storage shed for 4000 tons of china clay transported to the Westbrook paper mill in PTM box cars.