How are the boundaries of the world divided?

National boundaries are determined by treaties signed by neighboring countries through consultation. However, there are exceptions. Some areas are not treaty boundaries, but traditional customary boundaries. According to the method of dividing national boundaries, national boundaries can be divided into natural boundaries and artificial boundaries.

Natural boundaries, also known as natural boundaries, refer to the national boundaries defined by natural geographical boundaries that hinder traffic, such as mountains, rivers, lakes, oceans and deserts. Natural boundaries are clearly defined by relevant countries through relevant agreements, but border disputes often occur because of different views held by all parties. In order to accurately demarcate national boundaries, according to international practice, when natural geographical features are taken as the borders of neighboring countries, mountains are mostly bounded by watersheds, such as the watershed in the Pyrenees, which constitutes France and France. Navigable rivers are bounded by the center line of the main channel, and non-navigable rivers are bounded by the center line of the river. For example, most of the border between eastern China and Russia is bounded by the center lines of the main waterways of Heilongjiang and Wusuli rivers; A lake or inland sea is bounded by a straight line connecting the center line or end point of the land boundary between the two sides of the Taiwan Strait. The former is Lake Superior between the United States and Canada, and the latter is Lake Xingkai between China and Russia. The method of delimitation of straits is similar to that of rivers.

Man-made boundaries mainly include: ① mathematical boundaries, that is, national boundaries divided by latitude and longitude. 44% of the borders of African countries belong to mathematical borders, and most of the borders between the United States and Canada formed by the 49 north latitude line are the longest mathematical borders in the world. (2) Geometric boundary refers to the boundary between two measuring points connected by a straight line. For example, Algeria, Chad, Libya and other countries are mostly geometric borders. ③ Cultural boundary refers to the boundary divided according to various cultural factors.

Due to many reasons, such as the central line of the main channel of the river changes with hydrological conditions, the mountain ridge line does not coincide with the watershed, historical problems, the expansion policy of big countries, ethnic contradictions, religious conflicts, national strength differences, etc., many countries and regions in the world have serious border problems and territorial disputes, and even serious armed conflicts and wars, such as the four northern islands of Japan, the dispute between India and Pakistan and Kashmir, the sovereignty of Iran-Arabia River, and the Western Sahara issue.

In addition, national strength, population and capital are also important elements of a country's internal political geography.