Speed limits around the world — and why the US is the odd one out
The single most common mistake a US driver makes after crossing into Canada is to read a "100" sign as 100 mph. The single most common mistake a Canadian (or Japanese, or Korean) driver makes after entering the US is to read a "65" as 65 km/h. Speed limits are the most visually similar regulation across borders — and the one where the unit conversion will kill you.
Every country covered here posts speed in either mph or km/h, with no in-between. The numerical defaults differ widely, the camera-enforcement intensity differs even more, and school-zone reductions are universal but not standardised. We compare maximum highway limits, default urban limits, and school-zone reductions across the four countries below.
⚠️ Not legal advice. Traffic and insurance laws change. Verify with the official source before you drive. Full disclaimer.
Side-by-side comparison
| Country | Max expressway / highway | Urban default / school zone |
|---|---|---|
| 🇺🇸United States | 65–85 mph (105–137 km/h) | Texas SH-130 has the US's highest posted limit at 85 mph. Most rural Interstates: 65–75 mph. Urban: 25–35 mph. School zones: 15–25 mph typically when active. (FHWA Speed Limit Basics) |
| 🇯🇵Japan | 100–120 km/h | 100 km/h default expressway; 120 km/h on designated Shin-Tōmei and Tōhoku sections. Ordinary roads: 60 km/h default. School zones (during posted hours): 30 km/h. (Japan NPA — Traffic Rules) |
| 🇰🇷South Korea | 100–110 km/h | 100–110 km/h on most expressways. Built-up areas: 50 km/h default. School zones: 30 km/h enforced 24/7 (Min-sik Law). (KoROAD — Road Traffic Authority) |
| 🇨🇦Canada | 100–120 km/h | BC Coquihalla / Alberta certain sections: 120 km/h. Ontario 400-series: 110 km/h since 2022. Most provincial highways: 90–100 km/h. School zones: 30 km/h during school hours. (Transportation Association of Canada) |
Country detail
United States
The US is the only major Western country still on mph. Every regulatory speed sign in the country, including Hawaii and Alaska, is in mph. Default speed limits are set by state law in the absence of a posted sign — typically 65 mph on rural Interstates, 25 mph in business districts. School-zone enforcement is concentrated when amber beacons flash; fines are commonly doubled and many states make school-zone tickets non-waivable.
Japan
Japan posts km/h exclusively. The 1971 international-symbol adoption brought the red-bordered white circle that is now used everywhere. Default limits are unusually low for a developed country — 60 km/h on ordinary roads — reflecting Japan's historically winding two-lane geometry. Camera enforcement on expressways is heavy; both fixed Orbis-style boxes and gantry-mounted average-speed sections are common.
South Korea
Korea matches the international red-circle convention with Hangul or numerals. The 2020 Min-sik Law dramatically increased penalties for school-zone violations — serious accidents in school zones can carry imprisonment. The 50 km/h default urban limit is among the strictest in the OECD. Camera enforcement is extensive on expressways and in school zones.
Canada
Canada uses km/h via white vertical rectangle (the US-style MUTCD shape; the European-style red circle is rare). The unit switch from mph in 1977 was part of metric conversion. BC and Alberta have widespread photo radar; Ontario uses red-light cameras and limited automated speed enforcement in community-safety zones; Quebec is expanding camera enforcement on autoroutes.
Frequently asked
- What is the fastest legal speed in North America?
- 85 mph (137 km/h) on Texas State Highway 130 in the US. Outside Texas, 80 mph (130 km/h) is found on certain Utah, Nevada, and South Dakota Interstates. In Canada, 120 km/h (75 mph) is found on parts of BC and Alberta. None of these match Europe's 130 km/h on French and Italian autoroutes.
- Do I need to convert speeds in my head?
- Rental cars in Canada and Japan show km/h primary. US rental cars show mph primary with a smaller km/h ring. The conversion: divide km/h by 1.609 to get mph, or multiply mph by 1.609 to get km/h. A 100 km/h sign is 62 mph; a 65 mph sign is 105 km/h.
- Are school-zone limits 24/7 or only during school hours?
- Varies by country and by zone. US: typically during posted hours or when amber beacons flash. Japan: typically during posted hours. Korea: 24/7 under the Min-sik Law. Canada: typically during posted school hours. Always read the small text plate beneath the speed sign.
- How aggressive is speed camera enforcement?
- Japan and Korea use the heaviest camera enforcement, including average-speed sections that measure your speed across two cameras. BC and Alberta (Canada) have widespread photo radar. US camera enforcement is patchier — common in some states (Maryland, Arizona historically) and prohibited or limited in others.
Sources
- [1]FHWA — Speed Limit Basics — FHWA · accessed 2026-04-23
- [2]National Police Agency — Rules of the Road — Japan NPA · accessed 2026-04-23
- [3]KoROAD — Road Traffic Authority — KoROAD · accessed 2026-04-23
- [4]Transportation Association of Canada (TAC) — TAC · accessed 2026-05-01