Montreal’s Locks

Have You Heard of Montreal’s Locks?

True pillars of river navigation, locks are engineering marvels that determine the size and weight of vessels that can pass through them. In Montreal, the locks of the Lachine Canal do more than facilitate boat traffic—they’ve had a profound impact on the city’s urban landscape. While today’s five locks share technical characteristics, each one has a unique story.

Dive into the fascinating history of Montreal’s locks, located near the port, whose construction began in 1824. But first, let’s take a look back at the origins of the Lachine Canal, from its earliest sketches in the 17th century to its official opening in 1825, including the many challenges faced along the way.

From Dream to Reality: The Birth of a Navigable Route in Montreal

The Lachine Rapids were long seen as a formidable obstacle for navigators. As early as 1671, François de Salignac de La Mothe-Fénelon proposed to the King that a canal be dug between Montreal and Lachine. The idea was taken up by François Dollier de Casson, superior of the Saint-Sulpice Seminary, and initial work began in 1689. The project was quickly halted. A second attempt was launched in 1700 under Gédéon de Catalogne, but it ended with his death in 1701.

In the 19th century, economic and military considerations revived the project. In 1815, Governor Sir George Prévost recommended cooperation between Lower Canada and the imperial government. In 1818, an ambitious route was proposed, but an economic crisis cooled the momentum. In 1819, local entrepreneurs formed the Lachine Canal Company, which ultimately failed to secure the necessary funding.

The project finally came to life in 1821 with imperial financial backing. Construction began on July 17. Despite high costs and urbanization challenges, the work progressed. In 1824, the location of the Montreal locks was determined. The canal was officially inaugurated on August 24, 1824, and by 1825, boats could navigate its full length. Stretching 15.5 km and equipped with seven locks, the canal allowed vessels to bypass the dangerous Lachine Rapids by overcoming a 13-metre elevation difference.

The History of Montreal’s Locks: From 1824 to Today

Originally, three locks were built in Montreal, not without difficulty due to the proximity of the St. Lawrence River. To stabilize the sandy ground, piles were installed, along with a wharf and a jetty, still located today near De la Commune and Mill streets. With limited access to water, two wells were dug to provide residents with drinking water. The northern sector of De la Commune Street was reserved for merchants needing storage space.

Lachine Canal, Lachine, Quebec, circa 1850. © McCord Museum, M984.273.

In response to increased maritime traffic, two canal levels (or “reaches”) were added in the 1830s. Then, in the 1840s, the locks were widened to accommodate larger ships. In 1844, the number of locks in Montreal was reduced from three to two. By 1848, they measured 61 metres long by 14 metres wide and 2.75 metres deep—large enough to receive ocean-going vessels.

In 1871, Canada modernized its canal network to stimulate interprovincial trade. Between 1875 and 1879, Montreal’s locks were twinned. A new entrance to the port reshaped the landscape with two parallel locks, a basin, and a jetty. By the 1930s, over 10,000 passages were recorded annually.

The locks remained in operation until they were filled in between 1965 and 1967. They were rediscovered during the redevelopment of the Old Port from 1990 to 1992. Since 2010, they have been managed by Parks Canada, standing as living witnesses to a rich industrial and maritime heritage.

A Transformed Landscape

The Lachine Canal is more than a navigable waterway—it is a true multifunctional corridor. This corridor integrates a complex network of infrastructure (railways, roads, bridges, power lines), all weaving around the canal. Added to this are vital port facilities such as wharves, side basins, and transshipment and storage equipment. The industrial complexes lining the canal, or located nearby, tell the story of Montreal’s and Canada’s industrialization.

Some of these elements are still visible today, particularly near the Montreal locks, silent witnesses of a thriving industrial past

Once part of Reach No. 2, it served as a junction between inland and ocean-going navigation. A true window onto the Atlantic, the basin allowed ships to transfer cargo or perform turning maneuvers. This landmark, still visible in today’s urban landscape, is a powerful reminder of the canal’s strategic role in maritime trade. Among these iconic infrastructures, the Peel Basin holds a special place.

From Industrial Age to Urban Redevelopment

By the mid-19th century, industrialization had radically transformed the canal’s surroundings. The banks rapidly filled with factories, warehouses, and port infrastructure, making the Lachine Canal one of the country’s largest manufacturing hubs. But prosperity didn’t last forever. As deindustrialization set in, large industrial sites were abandoned. Commercial navigation ceased, and the canal entered a new era.

This shift marked the beginning of a major urban transformation. Demolitions, residential conversions, commercial projects, and new construction began to reshape the area. In 2025, this redevelopment is still underway, deeply transforming the social and residential fabric of surrounding neighborhoods. While necessary for revitalization, these changes also raise questions about preserving heritage.

Balancing Memory and Modernity

Today, the Lachine Canal, designated a National Historic Site, sits at the heart of a rich and complex reality. Every new development must consider the site’s history and strive to protect its heritage values. Like a machine in constant evolution, the canal corridor is built, dismantled, and reinvented through the ages, shaped by technologies, needs, and the changing rhythms of society.