The Pan-American Highway is a network of roads measuring about 47,958 kilometers in total length. Extending north from Alaska and south to Tierra del Fuego, except for a break between the Darién Province in Panama and the Colombian border, the road links the mainland nations of the Americas in a connected highway system. According to the Guinness World Records, the Pan-American Highway is the world's longest "motorable road".

The Pan-American Highway passes through the entire American continent including many diverse climates and ecological types, from rainforests, to deserts, to cold mountains. The high way crosses a dozen countries with different road conditions and markings, some stretches of the highway are passable only during the dry season, and in many regions driving is occasionally hazardous. Therefore, the Pan-American Highway is also regarded as one of 40 most dangerous roads all over the world.

A notable break in the highway is a section of land between Panama Canal and the Colombian border called the Darién Gap. It is an 87 kilometers stretch of rainforest. Vehicle drivers have to take a ferry to move the vehicles to Venezuela or Colombia, and then, continue their trip on the highway.

The Pan-American Highway provides transportation channels for agricultural products and raw materials. The famous sections of the Pan-American Highway include the Alaska Highway and the Inter-American Highway. The latter connecting the United States with the Panama Canal, is the most commonly used driving route to Mexico by travelers.

Source:
http://baike.baidu.com/view/67176.htm
http://en.wikipedia.org/wiki/Pan-American_Highway