The usage of these white oval decals originated in Europe in the early 20th century. European countries are relatively small and drivers have always frequently crossed from country to country. Moreover, in those days European licence plates all looked confusingly similar, so Europe needed to find an easy way to identify each vehicle’s country of registration. They came up with the idea of making it mandatory to put a white oval-shaped sticker with black country initials on the back of all vehicles.

This European custom became an international requirement in many countries after the U.N.’s Geneva Convention on Road Traffic (1949) and Vienna Convention on Road Traffic (1968). It was agreed upon that a distinguishing sign of the country of registration had to be displayed on the rear of the vehicle. It also stipulated that the sign could either be placed separately from the registration plate or could be incorporated into the vehicle’s number plate and if the international registration letter was incorporated into the licence plate, it also had to appear on the front number plate.

These days, oval stickers with an international circulation mark are not as common anymore in Europe, since standard E.U. number plates have integrated the country code into a blue strip on the left side of the plate. This blue section is actually the flag of Europe (a circle of 12 yellow stars on a blue background), with the country code of the member state underneath it.

Since only two countries border the United States and the vast majority of Americans, Canadians and Mexicans hire a car instead of bringing their own when they go abroad, there was no need for car ovals at all. This explains why these oval-shaped country stickers have never been subject to any kind of regulation by the American Government. At some point in the early 80s, however, it became trendy for Americans to look European: with the yuppie bimmer craze, it was not uncommon to see BMWs with the German “D” oval sticker (Deutschland) driving on American highways (see picture on the left).