Canada's First Electric Telegraph
19 December 1846 marked the inauguration of the telegraph in Canada. This major development in communications was pioneered by the Toronto, Hamilton and Niagara Electro-Magnetic Telegraph Company whose line then being built between Toronto and Queenston carried the first message, from the mayor of Toronto to his Hamilton counterpart. To most Canadians the early telegraph was an expensive novelty but both the press and business soon adapted it to their use. In 1852 the successful but limited Toronto, Hamilton and Niagara enterprise was bought by the larger Montreal Telegraph Company.
Plaque via Alan L. Brown's site Toronto Plaques. Full page here.