There have been several westward migrations in American history.

History of American Western Development:

1776 when the United States became independent, it only knew the Atlantic coast, covering an area of about 400,000 square miles. However, as a British colony, it was established on the basis of capitalism from the beginning, with a history of 175 years, and its western region was 6.5 times the virgin land of the United States at that time. 1748 the establishment of Virginia Ohio land company can be regarded as a sign that the United States began to engage in the development of the western region, but due to the British king's prevention, the progress was slow and it was not officially launched until the United States became independent.

The three land laws promulgated in 1784, 1785 and 1787 are the program for the United States to develop the western region: first, to declare the nationalization of land in the western region; Second, decide to open public resources to free immigrants; Third, it is stipulated that the new state established in the western region must adopt the system of * * *, and forced labor is not allowed.

The development of the western region caused a large-scale immigration movement in the United States. It first nationalized the land in the west, and then sold it to free immigrants at a low price, and combined the sale of public land with the granting and recognition of "preemption", so that agricultural land development, animal husbandry development, mining development, urban development and traffic construction interacted synchronously, thus giving the American economic revolution an explosive feature in the19th century. Thousands of independent farmers can develop freely on such a vast land without any feudal remnants, forming a pattern of all-round development of agriculture, mining, towns and railways with free land development as the core, which constitutes a classic period of western development in the United States.

This large-scale colonial movement lasted for more than 100 years even in terms of its basic and main process. With the mature period of American economy and overall development, that is, industrialization, the development of frontier as an important factor has played a long-term role in the development of a country, and it is so closely related to the development process of all aspects of this country. Such an example is rare, even unique, in the whole world history.

By the end of 19, the population center, agricultural center and industrial center of the United States moved westward, and at the same time pushed the United States from a weak country to the throne of a world economic power, and the total industrial output value jumped to the top in the world in 1895. From the development process, the development of the western United States can be divided into three stages: agricultural development stage (1750- 1850), industrial development stage (1850- 1950) and scientific and technological development stage (1950 to the present). At the same time, the focus of American economic development has changed accordingly. New England, the Midwest and California can be seen as several signs of this shift.