International vehicle codes and the country letters

On older photos of cars at a border you see a white oval on the back with one or two black letters: D, CH, F, GB. These international vehicle codes show which country a car is registered in. Some are clear at a glance, others read like a small puzzle. Behind both lie more than a hundred years of traffic history and a few quirks of language.

Where the ovals come from

The ovals are older than most people think. They were introduced by the Paris Convention on Motor Traffic of 1909, which came into force in May 1910. Back then the first motor cars were crossing borders, and there had to be a simple way to tell where they came from. Even the shape was fixed: a white oval, 30 by 18 centimetres, with black letters. Only one or two Latin letters were allowed per country. Today the details are set by the Vienna Convention on Road Traffic of 1968, but the basic idea is more than a century old.

Why some codes look strange

The tricky cases arise when a country uses not its English or German name but its own. The most famous is Switzerland. Its code CH stands for Confoederatio Helvetica, the country's Latin name. Latin, because Switzerland has four official languages and did not want to put one ahead of the others. A neutral letter code was the most elegant answer.

Other countries simply use their native name. Once you know the pattern, you can decode most of them in your head.

• D: Deutschland, one of the easy ones.
• CH: Confoederatio Helvetica, the Latin name of four-language Switzerland.
• HR: Hrvatska, what Croatia calls itself.
• IS: Ísland, Iceland's own name for itself.
• FL: Fürstentum Liechtenstein, the principality spelled out.

The obvious letters

Happily, most codes are straightforward. F is France, E is España and so Spain, I is Italy, P is Portugal. Often it is simply the first letter of the country's name in its own language. Germany's D belongs in this group, as does A for Austria. So you do not have to memorise the codes by rote; many you can just work out once you know the native name.

When a country changes its code

Codes are not fixed for all time. The United Kingdom switched from GB to UK in 2021 and formally notified the United Nations of the change. Inside the EU you barely need the sticker anyway: the number plate itself already carries the country letter in the blue strip on the left, and that is recognised across Europe. The little oval on the back is now mainly for trips beyond the EU.

In CountryRush it is flags and outlines rather than letter codes, but the reflex is the same: see a small mark and match the country at once. The Daily Trip trains exactly that quick recognition.