Is Highway 401 really North America’s busiest highway?

Traffic reporter Kyle Hocking looked at the data and compared it to other big cities in North America like Chicago and New York City.

By Kyle Hocking

It has often been said that Highway 401 is North America’s busiest highway, but is that actually true, and if so, what does it mean?

CityNews had a look through the data to try and find out how the 401 stacks up against other highways in the United States and Mexico.

How are traffic volumes determined?

To determine how ‘busy’ a specific highway is, many transportation agencies use a measure known as Average Annual Daily Traffic (AADT), which is the number of vehicles that travel a highway each day averaged over 365 days.

Traffic volumes are typically collected through the use of electronic traffic counters, and many agencies publish the data online every few years with some publishing their data annually.

CityNews chose only to include data from prior to the COVID-19 pandemic, as lockdowns had a significant impact on traffic patterns and some agencies have not released any data since the pandemic began.

Highways in Canada

The Toronto section of Highway 401 is, without question, the busiest stretch of highway anywhere in Canada.

The most recent AADT data published by Ontario’s Ministry of Transportation (MTO) is from 2019.

The MTO’s data shows that about 314,200 vehicles travelled the 401 in Scarborough on an average day in 2019, around 378,500 used the section through North York, and about 386,850 travelled the stretch through Etobicoke.

When averaged out, approximately 359,850 vehicles travelled the Toronto section of Highway 401 on a typical day in 2019, with the busiest section being between Renforth Drive and Highway 427, which had an average of 450,300 vehicles pass by.


Highway 401 near Keele Street as seen from Chopper 680 on Feb. 14, 2023. (CITYNEWS/Kyle Hocking)

The country’s second busiest highway is the Metropolitan Autoroute, which is the portion of Autoroute 40 that travels through downtown Montreal. It is also signed as part of the Trans-Canada Highway.

However, AADT data from Quebec’s Ministry of Transportation shows that in 2019, only about 167,000 vehicles travelled the heaviest section of that highway – the stretch between Rue Saint-Hubert/Christophe-Columb and Rue Jarry Est in Montreal – on an average day.

Highways in Mexico

AADT data from Mexico’s Secretariat of Communications and Transportation is released on an annual basis. The data shows that the busiest highways in the country are in the metropolitan areas of some of its largest cities, including Mexico City, Monterrey, and Guadalajara.

But, even Mexico’s busiest highway – a stretch of Mexican Federal Highway 54 in Monterrey – typically does not even exceed 100,000 vehicles per day on average.

mexico traffic

FILE – In this March 30, 2016, file photo, cars sit in evening rush hour traffic in Mexico City. (AP Photo/Rebecca Blackwell, File)

In 2019, the most used section of the highway between Monterrey Centro and Ciudad Apodaca, a suburb to the northeast of downtown, saw an average of 95,232 vehicles travel it each day.

Highways in the United States

There are, of course, many busy highways in the United States, but for the most part, traffic volumes down south still pale in comparison to Highway 401.

One of America’s busiest highways is the Dan Ryan Expressway through Chicago, which features an express and collector system similar to the 401.

But, AADT data from the Illinois Department of Transportation shows that in 2016, an average of just 297,940 vehicles used the Expressway between Interstate 290 near downtown Chicago and Interstate 57 in the city’s south side.

In California, the 405 Freeway in Los Angeles is often pointed to as one of the nation’s most notoriously cramped highways as well. Though it is the busiest highway in Los Angeles, AADT data from California’s Department of Transportation – known as Caltrans – shows lower traffic volumes than on Highway 401.

About 269,420 vehicles travelled through L.A. County, and 269,313 vehicles travelled through Orange County per day on average in 2017.

I-405 Los Angeles LA traffic

Traffic is jammed along Interstate 405 in Los Angeles during rush hour ahead of Thanksgiving in Nov. 2016. (ABC7/Youtube)

The Long Island Expressway in Queens, N.Y., near New York City, is another perpetually busy route. It is the most heavily travelled highway in the Tri-State area, but according to New York’s Department of Transportation, AADT data found far less volume than Highway 401 in 2016 – just 224,901 vehicles on average.

For comparison, 2016 AADT data for Highway 401 showed an average of 331,084 vehicles traveling the Toronto stretch of the highway each day.

Highway 401 takes the title

A look at the data shows that the 401 is, in fact, North America’s busiest highway. And even though it’s really nothing to boast about, it does give us an odd sense of pride, doesn’t it?

It’s still yet to be seen if the COVID-19 pandemic will have left any kind of a long-term impact on traffic volumes, but as more data is released in the coming years, that will come into sharper focus.

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