In the late 17th century the site was occupied, perhaps intermittently, by members of the d'Ailleboust family, who used "sieur de Coulonge" as a title. Accounts differ: the
Commission de toponymie du Québec mentions Nicholas d'Ailleboust de Manthet, who wintered in that location in 1694; The trading post became the village of Fort-Coulonge situated several kilometres down river, when in 1843, the region's first sawmill was built by
George Bryson Sr. This was the impetus that led to permanent settlement and the formation of the village. Two year later in 1845, the mission of Saint-Pierre-de-Fort-Coulonge was established, followed by the Presbyterian parish of St. Andrews in 1863. Its post office opened in 1853. By the mid 1860s, the town had a population of about 500. The first wooden chapel was built in 1873. It was destroyed by fire and replaced by a brick church in 1884. In 1886, the
Pontiac Pacific Junction Railway reached Fort-Coulonge. Fort-Coulonge became a municipality in 1888 when it separated from the Township Municipality of Mansfield.
John Bryson, son of George Bryson, was the first mayor. The lumber industry continued to drive the growth of Fort-Coulonge in the 1890s and early 20th century. The many logging camps in the Ottawa Valley created a big demand for accommodation in the town; by the 1890s there were at least 5 hotels. The town's mills produced thousands of feet of cut lumber, as well as
pulp wood. In passenger rail service to Fort-Coulonge ended in 1958, and cargo traffic ended in 1977. == Demographics ==