1. The United States is located in the central part of North America, with an area of about 9.629 million square kilometers (including 91589.6 million square kilometers of land area, about 200000 square kilometers of inland waters, and about 170000 square kilometers of the U.S. sovereign part of the five Great Lakes).
 2. The area of estuaries, harbours, inland seas and other coastal waters is about 100000 square kilometers, accounting for 6.3% of the world's land area, ranking fourth in the world.
 3. The state-controlled territory of the United States also includes Alaska in the northwest of North America and the Hawaiian Islands in the central Pacific Ocean.
 4. It borders Canada to the north, the Gulf of Mexico to the south, the Pacific Ocean to the west, and the Atlantic Ocean to the east.
 5. It is 4500km long from east to west, 2700km wide from south to north, and 22680km long coastline.
 6. Most areas have a continental climate, while the south has a subtropical climate.
 7. The temperature difference in the central and northern plains is very large. The average temperature in Chicago is - 3 ℃ in January and 24 ℃ in July; The average temperature along the Gulf Coast is 11 ℃ in January and 28 ℃ in July.