Yes, but there isn't much traffic. Only used for time-sensitive stuff or items far inland that are already on railroad network. Roads up there can get really bad, and aren't great at their best. Shipping all of it by sea would probably end up saving money. Just slower.

I wonder how the USA will sabotage Canada's trade with Mexico? Less than 15% is moved by air or sea, the rest by truck and rail through the USA. I could certainly imagine an orange buffoon blocking all of that surface transport, or effectively blocking it with a ridiculous through-traffic fee.