North America is the third largest continent, with a surface area of 24,221,490 sq km (9,351,969 sq miles). It is located in the northern hemisphere, between the Pacific Ocean and the Atlantic Ocean and to the north of South America. North America's highest point is Alaska's Mount McKinley, which rises to 6,194 m (20,320 ft) above sea level.
North America consists of three large nations and one large island territory that covers most of its area. They are Canada, the United States of America (USA), Mexico and Greenland. There are also seven smaller nations at its southern extreme (collectively known as Central America), around two dozen island nations and territories of various sizes in the Caribbean, and one isolated French territory off the Canadian Atlantic coast. Although the Central American and the Caribbean regions are technically part of the North American continent, they are commonly listed separately from their larger neighbors to the north and hence the distinctive region names for both cultural and geographical reasons.
Because population centers are often widely spaced, most long-range travel is by air, with an extensive network of major hubs and smaller regional airports, usually supplemented with car rental services to cover local travel (see "By car").
There is prolific long range bus service across most of the US and Canada, but travel times are excessively long (on the order of three to five times as long as a direct trip in a personal vehicle) and many stations are relatively unsafe. Most bus service is useful only for traveling within a dense metro area or along major commuter routes and is then limited or unavailable outside of business hours.
Most travel in Canada, the United States, and Mexico is by personal vehicle. Almost all highways in Canada and the United States are well maintained, with amenities such as gas, food, and lodging ranging from adequate to very convenient to excessive. If you experience an emergency that endangers your life, safety, or property, you will be able to dial 911 from a compatible cell phone on almost any major highway and reach an operator at any time. Vehicle and medical insurance issued in either Canada or the U.S. is usually valid in the other, though the wise traveler will confirm with their insurer. Canada and U.S. insurance coverage in Mexico is sometimes limited or not honored. Again, the wise traveler will confirm with their insurer.
Car rental agencies are available at almost every airport. Usually a major credit card and proof of liability insurance is required. Some agencies offer short term insurance and additional coverage.
Although it once held much of the continent together, and remains useful for local travel in many metro areas, intercity train travel now ranges from relatively convenient in the Northeast Corridor, to manageable in California and parts of southeastern Canada, to sparse in other parts of the continent. If you prefer to travel by rail, it's still possible (depending on where you go), but it offers neither speed nor convenience. As noted above, the exception is the Northeast Corridor area, which links Washington, D.C. to Boston with frequent stops in intermediate cities such as Baltimore, Philadelphia, New York City, New Haven, and Providence. It is explained in detail on the Rail travel in North America article.