How on earth did the United States carry out the western development?

If any country has the strongest military power in the world today, it is undoubtedly the United States. The strength of the United States cannot be separated from the previous western development. The United States is a country composed of Washington, D.C. and 50 states, and its national culture is diverse. Most life in the United States is concentrated in the settlements of primitive Indians. 1775, the American people broke out the war of independence against the colonial rule of the British Empire. The war transformed America from a slave society into a capitalist country. The following June, George? Washington issued the Declaration of Independence, announcing the birth of the United States. The western development of the United States began as early as the British rule. At that time, slave owners and the rich wanted to own the rich areas in the western United States. But at that time, the west was under British rule. 1763, the British issued a decree prohibiting all people from going to the western United States through immigration. And send troops to guard the only way to the west. When the United States declared its independence, the American government began to expand to the west of the Mississippi River. They bought their colonies in the western United States with Britain, France, Spain and other countries in the form of capital transactions, and finally expanded the whole western region into a part of American territory through war plunder. Eventually, the territory of the United States gradually expanded, and they thoroughly developed the western region, where they developed industry and agriculture. The American economy is developing rapidly. The development of the western region has expanded the cultivated land area in the United States and fully developed the agricultural economy in the United States. Therefore, the western development of the United States has pushed the American economy to a climax.