The United Statesis situated almost entirely in the western hemisphere. The contiguous (连续的，邻近的) United States stretches from the Pacific on the west to the Atlantic on the east, with the Gulf of Mexico （墨西哥湾） to the southeast. It is bordered by Canada on the north and Mexico on the south.

Mainland USA is situated in southern part of North America. The north of the country shares more than 6,000 kilometers of land boundary with Canada, which runs along the 49th parallel （北纬49度线） in the west and then goes across thefour of the five Great Lakes （北美五大湖）, ending at the Atlantic（大西洋） Coast. The boundary between America and Canada is open and undefended.

The southern land neighbor of the United States is Mexico, with which it shares a common boundary of some 3000 kilometers, starting near the mouth of Colorado River（科罗拉多河）, continuing through the lower reaches of the River and ending at the Gulf of Mexico. The American government has established some Mexico-United States Barrier（美墨边境墙） along its border with Mexico with the purpose of preventing drug traffickers and illegal immigrants from stealing into the US.

On the west of the US mainland is the Pacific Ocean（太平洋）, across which the United States trades its products for goods from the Far East（远东，即亚洲）. On the east of the country lies the Atlantic Ocean which witnessed large numbers of European immigrants sailing to their land of opportunities. The Atlantic is still the most important sea routed from America to Europe and the Middle East.