The population of the United States migrated from the northeast to the south after the war. The main reason for moving westward.

From the discovery of American continent, the composition of American population and topography, we can draw the main reasons for this situation.

First of all, the American continent was discovered and landed by western Europeans, and the Atlantic Ocean is actually not wide, so it can often travel between the two places.

Second, the demographic composition of the United States. In the early days, the population of the United States consisted entirely of European colonists, pirates and criminals from various countries. These people traveled back and forth to the American continent in droves, plundering and slaughtering the aborigines crazily. During the world war, they even sold people from Asian and non-Asian countries to America as slaves and exploited the American continent. These people are at the bottom and constitute the population except white Americans.

Third, the terrain. The American continent is vertical from north to south, slightly narrower from east to west, with oceans on both sides, a narrow Atlantic Ocean and a wide Pacific Ocean. Europe in the west and the Pacific Ocean in the east.

From the above three points of view, the eastern part of the United States near the Atlantic Ocean was first discovered and developed, and it is the best in both economy and all aspects. Various industries are also concentrated there, and urban agglomerations are also concentrated in that area. With the increase of population, the resources in the eastern coast of the United States began to be tense, and population migration was imperative. At that time, the western and southern parts of the United States were vast and sparsely populated, and they were in urgent need of development. As a result, the government-guided population migration began. In order to guide these people to migrate, the United States has formulated many policies, including the nature of land, funds and population. In terms of land, it adopts a similar way of staking, and whoever develops it is allowed to equip them. This is the origin of the name cowboy. In terms of funds, regardless of the source of funds, a large number of black money poured into development funds and even allowed gambling. This is how the desert city of Las Vegas developed. In terms of population nature, there is no restriction and fugitives are allowed. In a word, the United States makes every effort to develop these wasteland.

The population migration in the United States did not begin after the war, but before the First World War, only on a larger scale. The main reason for this immigration is similar to China's "western development", but the difference is that China only has so-called policies, and there is no immigration, while the United States moved as a whole to develop the wasteland in the United States.