Widely regarded as one of the greatest engineering achievements of its era, the Canadian Pacific Railway was the first transcontinental rail line to span the young country from coast to coast. Stretching over 4,600 km from Montreal to the Pacific port of Port Moody, near present-day Vancouver, it was for decades the longest railway in the world. The overall design required hundreds of timber trestles, dozens of tunnels blasted through solid rock, and a winding route over several mountain passes. Remarkably, much of the original alignment through the Rockies is still followed by trains today.

The motivation for the railway's construction came largely from a promise. When British Columbia agreed to join the new nation of Canada in 1871, the federal government pledged to build a rail link to the Pacific within ten years. Without such a line, leaders feared the western colony might drift toward its southern neighbour. A railway, they argued, would bind the scattered provinces together and open the prairies to settlement. The project posed severe logistical and financial challenges, since the chosen route crossed vast muskeg, the rugged Canadian Shield, and the formidable barrier of the mountains.