An earlier Cornwall County existed from 24 September 1804 until 4 February 1813 as an administrative division whilst Van Diemen's Land was administered as two units.

It was defined as all of Van Diemen's Land north of the 42nd parallel (now between Trial Harbour and Friendly Beaches), and governed by William Paterson.

[3] There was, until 1999, a state electoral division of Cornwall occupying a similar area to the district.

On 15 January 1836 George Arthur, the Lieutenant Governor of the Island of Van Diemen's Land proclaimed, via The Hobart Town Courier, the first counties and parishes to be surveyed in the colony.

[4]Hundreds and parishes proclaimed at this time were: The townships of Launceston, Hadspen, Perth, Avoca (portion of) were delimited in the same proclamation.