A plain-language reference for fleet and commercial operators in Southwestern Ontario. The 401 and the 402 are not just two highways through the region — they are the two land routes that feed the busiest commercial bridges between Canada and the United States. This article is the data file, with the primary sources, the methodology notes, and the figures laid out cleanly. The framing matters — it is the corridor as a single freight system, not the 401 as a stand-alone highway, where the numbers actually land.
If you run trucks in Southwestern Ontario, the 401 and the 402 are not abstractions. They are the routes you plan around, the surface your drivers drive on every working day, and — at their two ends — the bridges your loads cross to reach the United States.
This article is the data file behind that. What the freight numbers actually say about the corridor, where the figures come from, which figures hold up under scrutiny and which don't, and what stays true once the comparisons get sorted out.
The headline is short and earns the rest of the article: the 401 feeds the Ambassador Bridge at Windsor; the 402 feeds the Blue Water Bridge at Sarnia. Those two bridges, in 2024, carried US$192.6 billion in truck freight between Canada and the United States — 45.6% of all US-Canada truck freight by value, and roughly a quarter of total Canada-US merchandise trade across every mode of transport combined.
Every figure that follows is from the primary source it cites. Where the published numbers conflict or the methodology is loose, that is flagged rather than papered over.
Highway 401 runs east-west across Southern Ontario, from Windsor at the US border to the Quebec line, with Toronto roughly in the middle. Highway 402 branches off at London and runs west to Sarnia, where it meets the Blue Water Bridge. Together the two highways form a Y-shape that connects the two busiest Canada-US commercial truck crossings — Ambassador Bridge at the foot of the 401, Blue Water Bridge at the foot of the 402 — to the rest of the province and, beyond it, to Quebec and Atlantic Canada.
A truck moving high-value goods between the US Midwest and Central Canada is, with very few exceptions, on one of these two highways and crossing at one of these two bridges. That is what the freight numbers below describe.
The cleanest figure available is from the US Bureau of Transportation Statistics, which publishes annual port-level freight value by mode through its TransBorder dataset. The 2024 annual report — released in March 2025 — is the most recent full-year picture.
By truck freight value, two-way, the top five US-Canada land ports in 2024 were:
| Rank | Port of entry (Canadian counterpart) | 2024 truck freight, two-way | Share of US-Canada truck freight | Year-over-year |
|---|---|---|---|---|
| 1 | Detroit, MI (Windsor / Hwy 401) | US$114.15 B | 27.0% | −10.1% |
| 2 | Port Huron, MI (Sarnia / Hwy 402) | US$78.47 B | 18.6% | +10.0% |
| 3 | Buffalo-Niagara Falls, NY (Fort Erie / Niagara / Queenston) | US$72.33 B | 17.1% | −2.7% |
| 4 | Pembina, ND (Emerson, MB) | US$24.10 B | 5.7% | −4.3% |
| 5 | Champlain, NY (Lacolle, QC) | US$22.28 B | 5.3% | −4.1% |
Detroit and Port Huron together — the US-side endpoints of the 401 and the 402 — carried US$192.6 billion in two-way truck freight in 2024, or 45.6% of all US-Canada truck freight by value.
Set against the larger denominator — all US-Canada freight across all modes, which BTS puts at US$761.2 billion in 2024 — the same two ports carry roughly 25.3% of total Canada-US merchandise trade. The two framings answer different questions; both are defensible, and both should name their denominator out loud.
A per-minute figure follows from the same base number: US$192.6 billion of truck freight in a single year works out to roughly US$367,000 per minute, every minute of 2024, moving through the two ports the 401-402 corridor directly feeds.
The Ambassador Bridge at Windsor-Detroit has been described in trade-press copy as the busiest land border crossing in North America for decades. The claim is partly true and partly a function of which question is being asked.
By truck freight value, in 2024, the answer is yes: Detroit was the #1 US-Canada land port, with US$114.15 billion in two-way truck freight, and 27.0% of all US-Canada truck freight by value. That ranking comes directly from BTS TransBorder 2024.
By share of total Canada-US trade across all modes, the same Detroit port carried roughly 15.0% of the US$761.2 billion total. The "25-27% of all Canada-US trade" figure that circulates is correct as a share of US-Canada road or surface trade, but not as a share of all-modes trade — pipeline, rail, vessel, and air make up the rest of the larger denominator. The figure can be quoted; the denominator has to be named.
By truck count, the picture has changed. The Bridge and Tunnel Operators Association — the industry body that compiles bridge-by-bridge crossing data — reported that the Ambassador Bridge carried about 2.28 million truck crossings in 2024, the third-lowest year on record (only 2009 and 2020 were lower), and an 11.1% decline from 2023. The Detroit News reported the same figure in February 2025.
Across 2025, a structural shift continued: the Blue Water Bridge at Sarnia – Port Huron surpassed the Ambassador Bridge in monthly commercial truck trips every month of 2025, and the first quarter of 2026 has continued the same pattern. The driver is the toll differential — about $7 per axle at Blue Water versus up to $27 per axle at Ambassador — which has pulled cost-sensitive truck traffic north onto Highway 402. CBC News reported the year-over-year shift in April 2026 from the same Bridge and Tunnel Operators Association data.
The two facts coexist. Ambassador remains the higher-value crossing, because the automotive trade that dominates Windsor-Detroit moves high-value loads. Blue Water has become the higher-volume crossing by truck count. A 2026 customer-facing claim that names "the busiest crossing" has to name which metric — value or count — and then the answer follows.
For comparison against US-Mexico crossings: the Texas Comptroller's Port of Entry: Laredo 2024 report puts Laredo, TX at US$339.7 billion in two-way trade across all modes, with about 62% of Texas land-port trade flowing through it. Laredo is the #1 land port in North America by total trade value. Detroit ranks #2. The Canada-US corridor is Detroit-led; the all-modes North American picture has Laredo at the top.
The Blue Water Bridge connects Highway 402 at Sarnia to Interstate 94 at Port Huron, Michigan. In the BTS port-level numbers for 2024, it ranks as the #2 US-Canada land port by truck freight value, with US$78.47 billion in two-way trade and 18.6% of all US-Canada truck freight.
Two things about that figure stand out.
First, Blue Water carried more truck freight with Canada in 2024 than the entire Buffalo-Niagara cluster. Buffalo-Niagara Falls — which includes the Peace Bridge, the Lewiston-Queenston Bridge, and the Rainbow Bridge — totalled US$72.33 billion across all three crossings combined. Blue Water at US$78.47 billion exceeded that by about US$6 billion at a single bridge.
Second, Blue Water was the only top-five US-Canada truck port to post double-digit growth in 2024. Its two-way truck freight value grew 10.0%. Detroit fell 10.1%. Buffalo-Niagara fell 2.7%. Pembina fell 4.3%. Champlain fell 4.1%. The toll-driven shift in truck routing visible in the crossing-count data shows up in the value data as well — Sarnia is the bridge that grew last year.
The asymmetry between Ambassador (declining counts, holding value) and Blue Water (rising counts, rising value) is the corridor story of the past two years in one sentence.
A claim that surfaces in trade-press writing about the 401 is that it is the busiest highway in North America by annual average daily traffic. The claim has a defensible version and an indefensible version, and the two are worth separating because the data file gets quoted more often than the methodology.
The defensible version is geographically specific. The Ontario Ministry of Transportation's Provincial Highways Traffic Volumes publication — most recent edition 2021, no later edition released as of May 2026 — records the 401's Toronto segment between Renforth Drive and Highway 427 at an AADT of 450,300 vehicles per day in 2019. That figure is higher than the AADT recorded on Interstate 405 in Los Angeles (about 383,500), Interstate 75 through Atlanta (about 419,000), or Interstate 10 in Houston (about 320,892). It is not higher than Interstate 5 in Los Angeles, whose peak segment carries about 504,000 vehicles per day in recent FHWA data. The "busiest in North America" claim does not survive against I-5; the "among the busiest in North America" claim does.
The indefensible version is the unmodified one — "the 401 is the busiest highway in North America" with no segment named, no year cited, and no acknowledgement that the comparison vintages are different. The Canadian figure is from 2019. The US figures are from 2008 through 2019. AADT methodology is broadly comparable between MTO and FHWA — both annualize daily counts from automatic traffic recorders — but year-mismatched comparisons do not earn the unmodified claim.
There is also a geography problem from a Southwestern Ontario perspective. The 450,300 AADT figure is the 401 through Toronto, not the 401-402 corridor through the region this site serves. By the time the 401 reaches London, AADT drops to around 64,200 (MTO 2016). By the time it reaches Windsor, the figure is lower again. The traffic story for the Toronto segment is a Toronto traffic story; it is not the story of the corridor west of London.
What holds up cleanly for Southwestern Ontario is the freight-value story from BTS — not the traffic-volume story from MTO. That is the reason this article leans on the BTS data for its anchor figure and treats the AADT comparison as a secondary observation, properly bounded.
A few claims that circulate in writing about the 401 and the bridges are not in this article because the verified primary sources don't support them:
"The 401 is the world's busiest truck route, carrying 60% of all vehicular trade between Canada and the US." The 60% figure appears in mid-2000s federal and trade-press materials with no clearly identified primary source. BTS TransBorder 2024 places Detroit at 27.0% and Port Huron at 18.6% — combined 45.6% — of US-Canada truck freight by value. A higher figure for "vehicular trade" by some other denominator may be defensible historically; the 60% number on its own is not currently sourceable to a primary publication.
"The Ambassador Bridge carries 25-30% of all Canada-US trade." True for some definitions of "trade"; not true for "all-modes Canada-US merchandise trade." The denominator distinction has to be named for the figure to be defensible.
A specific commercial-vehicle AADT for the 401 or 402 in Southwestern Ontario. The most recent Ontario Commercial Vehicle Survey is the 2006-2008 edition. Newer truck-only AADT for specific Southwestern Ontario segments exists in MTO regional data, but is not in the published Provincial Highways Traffic Volumes series and would require a direct query to MTO Regional Traffic Sections.
"Ambassador Bridge is currently the busiest commercial truck crossing between Canada and the US." True for value, no longer true for truck count as of 2025. Blue Water surpassed Ambassador on monthly truck trips every month of 2025 due to toll-driven traffic re-routing.
This article will be updated as new primary data lands. The BTS TransBorder Freight Data Annual Report 2025 has been published as of May 2026 and shows total US-Canada freight at US$712.8 billion (down 6.4% year-over-year) with the Detroit-Windsor corridor at US$94.2 billion. The 2024 numbers are kept as the anchor here for stability across a year of trade-policy volatility, with a note that 2025 data is available for any reader who wants the most recent year.
The single most defensible framing of the data is the one that treats Highway 401 and Highway 402 as a single freight system feeding two ports, rather than as two separate highways with two separate bridges at the end.
Read that way, the corridor anchors 45.6% of all US-Canada truck freight by value and roughly a quarter of all Canada-US merchandise trade across every mode. Those two figures rest on the same BTS table; the difference between them is the denominator. Either one can anchor a conversation about what this stretch of road actually carries.
The structural reason the framing works is geographic. Every truck that crosses the Ambassador Bridge has either just driven the 401 or is about to. Every truck that crosses the Blue Water Bridge is either on the 402 right now or about to be on the 401 immediately east of London, where the two highways meet. The corridor is a single piece of working infrastructure, and its anchoring ports are two ends of the same Y.
That is the corridor B&J's trucks run on. The reasons that matters operationally — fuel availability along the route, cardlock coverage at the bridges, the supply chain that gets a litre of diesel from a Sarnia terminal to a yard tank in Cambridge — are a different article. This one is the data file.
The BTS publishes the TransBorder Freight Annual Report each March, covering the prior calendar year. The 2026 report — covering 2026 freight — will land in March 2027 and will be the next time the headline anchor figure can move materially. Monthly TransBorder data is available through data.bts.gov for readers who want to track the corridor between annual releases.
The Ontario Ministry of Transportation has not published a Provincial Highways Traffic Volumes update since the 2021 edition. When a later edition is released, the AADT picture for Southwestern Ontario segments will be the figure to refresh. Until then, the MTO 2021 publication remains the most recent authoritative source for Ontario highway AADT.
The Bridge and Tunnel Operators Association continues to publish monthly truck-count data through its member bridges. The Ambassador-versus-Blue-Water re-routing visible in 2025 may continue, stabilize, or reverse depending on toll decisions on either side — the figures will tell the story as it develops.
A named rep takes the call, not a queue. Tell us about your operation — we’ll sort coloured diesel, clear diesel, propane, and DEF in one conversation.
Standing routes across nine regions. Same rep year-round; off-hours emergency dispatch through the same number.
Marketing Intelligence by Candid