Cross-country guides

The same regulation looks very different in the US, Japan, Korea, and Canada. These guides put the four countries side by side — with primary sources for every number.

• Stop signs around the world — same idea, four shapes

  Why STOP signs look different across the US, Canada, Japan, and Korea — and what each shape says about local traffic culture.

• Speed limits around the world — and why the US is the odd one out

  Default speed limits, expressway maximums, school-zone reductions, and enforcement style compared across the US, Japan, Korea, and Canada. Every number cites the responsible agency.

• BAC (drink-driving) limits around the world — and why "one beer" varies so much

  Legal blood-alcohol limits for driving in the US, Japan, Korea, and Canada — plus the criminal-vs-administrative distinction, zero-tolerance laws for young drivers, and enforcement style.

• Seatbelt and motorcycle-helmet laws compared — US, Canada, Japan, Korea

  Front and rear seatbelt enforcement, motorcycle-helmet requirements, and child-seat rules compared across the US, Japan, Korea, and Canada.

• Headlights and daytime running lights — when are they mandatory?

  When must headlights or daytime running lights be on? Comparison of US, Japan, Korea, and Canada. Canada has had universal DRL since 1990; the US does not require them.

• Emergency numbers and roadside-assistance hotlines — quick reference

  Police, ambulance, fire, and roadside-assistance numbers for the US, Japan, Korea, and Canada. Plus what to say in each country if your language is not the national language.