Which Canadian highway is the busiest in North America by traffic volume?

Which Canadian highway is the busiest in North America by traffic volume? The answer is Highway 401 in Ontario.

Ontario’s Highway 401 is an approximately 828-kilometer controlled-access freeway running from Windsor to the Ontario–Quebec border. Its Toronto section is especially famous for extraordinary traffic volumes and is commonly described as North America’s busiest highway.

The road is the backbone of the Quebec City–Windsor Corridor, linking Ontario’s largest urban and industrial centers with Montreal and cross-border routes into the United States. In Toronto, the freeway uses a collector–express lane system, allowing through traffic and local entering or exiting traffic to be separated across parallel carriageways.

Traffic is not uniform along the entire route, so the superlative refers especially to its busiest urban sections rather than every kilometer. Around Toronto, daily counts have exceeded 400,000 vehicles on some sections. Highway 401 is also often confused with the Trans-Canada Highway, Canada’s coast-to-coast route; the two descriptions refer to different kinds of prominence.