9,809,155 sq km (3,787,319 sq miles).

9,809,155 sq km (3,787,319 sq miles).

27.6 per sq km.

Washington, DC.

543,213 (1996). Nineteen other cities have a population larger than that of Washington, DC. New York is the largest city, with a population of over seven million. Los Angeles, Chicago, Houston, Philadelphia, San Diego, Phoenix and Dallas had estimated populations of over one million in 1994.

Covering a large part of the North American continent, the United States of America shares borders with Canada to the north and Mexico to the south and has coasts on the Atlantic, Pacific and Arctic oceans, the Caribbean Sea and the Gulf of Mexico. The State of Alaska, in the northwest corner of the continent, is separated from the rest of the country by Canada, and Hawaii lies in the central Pacific Ocean. One of the largest countries in the world, the USA has an enormous diversity of geographical features. The climate ranges from subtropical to Arctic, with a corresponding breadth of flora and fauna. For a more detailed description of each region's geographical characteristics, see the individual State sections.

Federal Republic since 1789. Gained independence from the UK in 1776. Head of State and Government: President William Clinton since 1993.

English, with significant Spanish-speaking minorities.

Protestant with Roman Catholic, Jewish and many ethnic minorities. In large cities people of the same ethnic background often live within defined communities.

The USA is divided into six time zones: Eastern Standard Time: GMT - 5 (from Apr-Oct: GMT - 4). Central Standard Time: GMT - 6 (from Apr-Oct: GMT - 5). Mountain Standard Time: GMT - 7 (from Apr-Oct: GMT - 6). Pacific Standard Time: GMT - 8 (from Apr-Oct: GMT - 7). Alaska: GMT - 9 (from Apr-Oct: GMT - 8). Hawaii: GMT - 10. Note: When calculating travel times, bear in mind the adoption of Daylight Saving Time (DST) by most States in summer. From the first Sunday in April to the last Sunday in October, clocks are put forward one hour, changing at 0200 hours local time. Regions not observing DST include most of Indiana, all of Arizona and Hawaii.

110/120 volts AC, 60Hz. Plugs are of the flat 2-pin type. European electrical appliances not fitted with dual-voltage capabilities will require a plug adaptor, which is best purchased before arrival in the USA.

Telephone: Full IDD is available. Country code: 1. Outgoing international code: 011. For emergency police, fire or medical services in major cities, dial 911. Fax: There are bureaux in all main centres, and major hotels also have facilities. Fax services are very widely available. Telegram: These can be sent through all telegraph and post offices. Post: There are only a limited number of post offices, so it is advisable to buy stamps in bulk. There are, however, stamp machines in hotels and shops, but these have a 25% price mark-up. Airmail to Europe takes up to a week. Post office hours: 0900-1700 (24 hours at main offices in larger cities). If sending gifts valued at less than US$50 to the USA, the recipient will not have to pay tax if the package is marked 'Unsolicited Gift'. Press: The most influential papers are The New York Times, Washington Post, Los Angeles Times and the Wall Street Journal. Owing to the high degree of self-government of each State, newspapers tend to be regionalised, although recent economic pressures have resulted in large-scale mergers. Even so, the USA publishes more newspapers than any other country, and has perhaps the bulkiest Sunday newspapers in the world, particularly the Sunday edition of The New York Times.