 The GMA developed some mines in the Eastern Cape Breton but mostly concentrated on the mainland part of Nova Scotia.In 1858, the GMA's monopoly was broken and many American-financed mining companies were developed in the area, particularly in Glace Bay, New Waterford, Sydney Mines and surrounding areas.In the 1890s, two large conglomerates were formed; the Dominion Coal Company (DOMCO) merged all the mines on the south side of Sydney Harbour and built the Sydney & Louisburg Railway with its headquarters in Glace Bay, to transport coal from the mines to the ports at Sydney and Louisbourg.