Border
Natural borders

Natural borders are geographical features that present natural obstacles to communication and transport. Existing political borders are often a formalization of such historical, natural obstacles.

Some geographical features that often constitute natural borders are:

Throughout history, technological advances have reduced the costs of transport and communication across the natural borders. That has reduced the significance of natural borders over time. As a result, political borders that have been formalized more recently, such as those in Africa or Americas, typically conform less to natural borders than very old borders, such as those in Europe or Asia, do.
keywords:existence