In the second half of the 16th century, St. Larwence Iroquoians lived in palisades villages in this area. By the middle of the 18th century, the Oswegatchie lived here. An agreement with the British in 1784 saw them move to what is now New York State.
In 1785, United Empire Loyalists settled in what is now Brockville. It was originally named Elizabethtown, the same as the township in which it sat. It was changed during the war of 1812 to honour General Isaac Brock.
By 1830, the population was 1,000. In 1832 it became the first incorporated self-governing town in what is now Ontario. By 1846, the population had doubled to over 2,000 and by 1869 5,000. A number of industries grew up here in the 19th century.
It became a city in 1962.
