Why does the Grand Canal in China run north-south?

In ancient times, there were two kinds of river transportation: natural river transportation and artificial canal. Natural river transportation has brought the convenience of transportation to mankind, both labor-saving, and economic, a reed of navigation, as long as the water power can be competent, with the waterway to reach all parts of its coast. Land transportation is not subject to the restrictions of the river, can be arbitrary, but in addition to open the flat land, hills and valleys, everywhere there are difficulties in transportation; and from the amount of transportation, the gap between the vehicle and the ship is very large, the force is also very different, the two comparisons, naturally, is the advantages of river transportation.

Of course, the natural river transportation also has its shortcomings and shortcomings, which is the river with the terrain of the high ground, and the river has a certain flow and flow problems, far from the river, the region, you can not get convenient. This gave rise to the method of artificial canalization to supplement the natural river...?

After the Grand Canal became the main waterway for water transportation, the canal transported grain to most parts of the country with the convenient conditions of the Grand Canal communicating between the north and the south, which became a powerful means for the dynasty to transfer materials and check and balance the society. Especially during the Ming and Qing dynasties, the social and historical role of the canal was fully realized.

The transportation of grain has always been the indispensable and most important material foundation for the maintenance of the central government. Especially after the ancient social and economic center of gravity shifted to the south, the political and military center of gravity and the economic center of gravity were separated, and the political and military significance of the canal transportation for the dynasties became more prominent. Year after year, the imperial court carried out the transportation of grain from the south to the north, which supplied the daily food for almost all the people living in the capital and greatly supported the normal operation of the entire central government. At the same time, the grain transport became an important material force to support the military system of the dynasty, and many of the huge local garrisons distributed all over the world, the defenses and offenses on the long borders, and the various battles in the four directions of the conquests were backed up by the grain transport as a strong material support.