In 1837 "an act to authorize the erection of the county of Simcoe into a separate district by the name of the district of Simcoe".

But Simcoe District wasn't proclaimed until 1843: "that the said county of Simcoe... shall be and compose a separate and distinct district, to be henceforth called and known by the name of the district of Simcoe."⁶

Most of the townships within the district did not see settlers until the 1830's. Most of the early settlers were of Scotch and Irish origin.

Simcoe District was abolished in 1849.

Simcoe District was located in Southern Ontario.