The Frank Slide was a rockslide that buried part of the mining town of Frank, Northwest Territories,[nb 1] Canada, on the morning of April 29, 1903. It occurred at 4:10 am, when over 82 million tonnes (90 million tons) of limestone rock slid down Turtle Mountain within 100 seconds, obliterating the eastern edge of Frank, the Canadian Pacific Railway line and the coal mine. It was one of the largest landslides in Canadian history and remains the deadliest, as between 70 and 90 of the town's residents were killed, most of whom remain buried in the rubble. Multiple factors led to the slide. Turtle Mountain's formation left it in a constant state of instability. Coal mining operations may have weakened the mountain's internal structure, as did a wet winter and cold snap on the night of the slide.
The railway was repaired within three weeks and the mine was quickly reopened. The section of town closest to the mountain was relocated in 1911 amid fears that another slide was possible. The town's population nearly doubled its pre-slide population by 1906, but dwindled after the mine closed permanently in 1917. The community is now part of the Municipality of Crowsnest Pass in the Province of Alberta and has a population around 200. The site of the disaster, which remains nearly unchanged since the slide, is now a popular tourist destination. It has been designated a Provincial Historic Site of Alberta and is home to an interpretive centre that receives over 100,000 visitors annually.