Borders

How borders get drawn

A border is a line two states have agreed on, or at least stopped arguing about. Some follow the land, like a river, a ridge or the line where rain runs off one way or the other. Others are geometric: a line of latitude or longitude, or a straight line between two points. Many of today's borders were drawn in the last two centuries, by treaties after wars, by colonial powers dividing territory, and by the break-up of empires.

When new countries became independent, they usually kept the boundaries they'd had as colonies or provinces, a principle known as uti possidetis. That's why so many borders in Africa and Latin America still follow lines drawn by distant governments. Each article here explains how one border came about, with the treaties and sources behind it.