Dundas County is a former county in the province of Ontario, Canada. It was named after Henry Dundas, 1st Viscount Melville, who was the British Home Secretary (1791–1794), with responsibility for the colonies. Dundas was first settled by individuals of European background in 1784, when German Loyalists who had fought with Sir John Johnson in the American Revolutionary War re-settled in Canada. The settlers were descendants of the Palatine immigrants to America in 1710.

Boundaries

In 1792, Dundas County was formally established by a proclamation of the Lieutenant Governor of Upper Canada, John Graves Simcoe, which established several counties in Upper Canada including Dundas. The boundaries of Dundas county were defined as follows: That the third of the said counties be hereafter called by the name of the county of Dundas; which county is to be bounded on the east by the westernmost boundary line of the county of Stormont, on the south by the river St. Lawrence, and on the west by the easternmost boundary line of the late township of Edwardsburgh, running north twenty-four degrees west until it intersects the Ottawa or Grand river, thence descending the said river until it meets the northwesternmost boundary of the county of Stormont. The said county of Dundas is to comprehend all the islands in the said river St. Lawrence nearest to the said county, in the whole or greater part fronting the same. Dundas originally stretched farther to the north, but in 1800, when Carleton County was established, parts of Dundas County were made part of Carleton County. The new boundaries for Dundas were as follows: That the townships of Williamsburg, Matilda, Mountain, and Winchester, with such of the islands in the river Saint Lawrence as are wholly or in greater part opposite thereto, do together constitute and form the county of Dundas. In 1850, Dundas united with Stormont and Glengarry to form the regional government United Counties of Stormont, Dundas and Glengarry.

Original townships