1775, the American people broke out the war of independence against the colonial rule of the British Empire. 1776 On July 4th, the Second Continental Congress was held in Philadelphia. George Washington was the commander-in-chief of the Continental Army and issued the Declaration of Independence, announcing the formal establishment of the United States of America. 1783 At the end of the War of Independence, Britain recognized the independence of 13 colonies. 1787, the constitution of the United States was passed, and a federal state was established.
The terrain of the United States:
The topography of the United States is varied, with high terrain in the west and low terrain in the east. There are coastal plains on the east coast, which are wide in the south and narrow in the north, extending to New Jersey and Long Island, and there are also some glacial sedimentary plains. Behind the coastal plain is a hilly area with undulating terrain, extending all the way to the Appalachian Mountains in North Carolina and New Hampshire, with an altitude of 1, 830 meters.
To the west of the Appalachian Mountains is the central plain of the United States, with relatively flat terrain. The Great Lakes and the Mississippi River Basin, the fourth largest river in the world, are also located here. To the west of the Mississippi River, the topography of the internal plain began to rise, and finally it entered the great plain with a vast area and few topographical features in the central United States.