Eastern Ontario was once manufacturing country. Before the auto plants of southern Ontario dominated the provincial economy, the rivers and canals of the east powered textile mills, flour mills, implement factories, and paper plants that employed thousands. Most of that industrial base is gone, but the buildings — built from local limestone and designed to last centuries — remain in various states of preservation and decay.
Almonte: Manchester of Canada
Almonte, on the Mississippi River in Lanark County, was the centre of Canadian wool manufacturing from the 1820s through the mid-1900s. At its peak, the town had half a dozen major mills producing blankets, tweed, and woolen cloth that was exported across the British Empire. The Rosamond Woolen Company was the largest, but Thoburn, Baird, and several smaller operations also lined the river.
The Mississippi River through Almonte drops significantly over a short distance, providing the water power that made the mills possible. The mill race system — engineered channels that diverted river water to drive turbines — is still partially visible. Some mill buildings have been converted (the Thoburn Mill is now residential), but others remain as substantial stone ruins. The best exploration is along the river walk through town, where you can see the full industrial landscape: mill buildings, dam structures, tailrace channels, and the infrastructure that supported a manufacturing economy.
Cornwall Cotton and Paper
Cornwall was built on cotton manufacturing and paper production. The Stormont Cotton Company, Canadian Coloured Cotton, and Courtaulds all operated major facilities in the city. The Domtar paper mill was another significant employer. The waterfront industrial district along the St. Lawrence was a working factory zone into the late 20th century.
Much of Cornwall's industrial heritage has been demolished, but substantial buildings remain along the waterfront and canal areas. The Cornwall Canal, now disused, has lock remnants and infrastructure from the pre-Seaway era. The canal itself is a fascinating artifact — it was built to bypass the Long Sault Rapids that the Seaway project later flooded entirely, making the canal redundant.
Smiths Falls
The Frost & Wood factory in Smiths Falls produced agricultural implements — plows, seeders, mowers — from 1839 to 1954. The operation was substantial: at its peak, Frost & Wood was one of the largest implement manufacturers in Canada, competing with Massey-Harris. Portions of the factory complex still stand along the Rideau River. The building scale gives you a sense of how significant manufacturing was to small Ontario towns before everything consolidated into a few large cities.
The other notable Smiths Falls industrial site is the former Hershey chocolate factory, which operated from 1963 to 2008. The loss of the Hershey plant was a major blow to the town. The building was subsequently repurposed as a Canopy Growth cannabis production facility — an unexpected second life that generated international media attention.
Merrickville and the Rideau Corridor
The Rideau Canal corridor has smaller-scale industrial ruins at several lock stations. Merrickville had a foundry, a woolen mill, and several smaller manufacturing operations powered by the canal. The ruins of the industrial blockhouse and mill sites near the locks are accessible and well-preserved. The canal itself, a UNESCO World Heritage Site, is the best-preserved example of a 19th-century slack-water canal in North America.
What Makes Eastern Ontario Different
The industrial ruins of eastern Ontario are distinctive because they were built from local materials — primarily limestone. Limestone construction is durable: walls that have stood since the 1840s are still structurally sound in many cases. This means that eastern Ontario's ruins are more photogenic and more substantial than the brick-and-frame industrial sites you find elsewhere in the province. The stone holds up. The roofs and floors do not, creating the distinctive roofless-stone-shell appearance that photographers find irresistible.