Arnprior is a town in Renfrew County, in the eastern portion of Southern Ontario, Canada. It is located at the mouth of the Madawaska River, as it enters the Ottawa River in the Ottawa Valley. The town is a namesake of Arnprior, Scotland, and is known for lumber, hydro power generation, aerospace, farming and its proximity to the national capital region.

In May 1613 European explorers, led by Samuel de Champlain, first visited the Ottawa River valley, home of the Algonquin tribe of native North Americans.

In 1823, a 1,200-acre (4.9 km2) surveyed block was ceded to Archibald McNab and given the eponymous name, McNab Township. McNab had approval from the Family Compact to treat the settlers on his land in the feudal manner practiced in Scotland. In 1831 the town was named by the Buchanan Brothers after McNab’s ancestral home of Arnprior, Scotland.

Tired of the harsh treatment, the settlers revolted and, after a government investigation, McNab was forced to vacate the area in 1841. Arnprior, Braeside and NcNab township grew as separate communities and boomed when they became incorporated into eastern Ontario’s massive timber industry.

One of the most successful businessmen of the upper Ottawa was Daniel McLachlin, who built a massive sawmill at the confluence of the Madawaska and Ottawa Rivers, and expanded the community of Arnprior. The lumber industry maintained a significant position until the closing of the Gillies Mill. One of the most enduring structures of the day was a grist mill built by the Buchanans on the west bank of the Madawaska River. The grey stone building served many purposes after it stopped being used as a grist mill, finally being operated as a restaurant and a gas station, first by the Beattie and then the Baird families, ending in 1974. The facility has been bought by Ontario Hydro prior to the restructuring on the bridge and the creation of a new weir to control the river. The building was consumed by fire in 1976. The forests of the period are represented in the Grove which is an excellent example of indigenous forest, grown after a fire in the 18th century. With individual specimens reaching 175 feet (53 m), these are the tallest white pines in Ontario.