Infrastructure
Smaller or less-developed airports—which represent the vast majority—often have a single runway shorter than 1,000 m (3,300 ft). Larger airports for airline flights generally have paved runways 2,000 m (6,600 ft) or longer. Many small airports have dirt, grass, or gravel runways, rather than asphalt or concrete.
In the United States, the minimum dimensions for dry, hard landing fields are defined by the FAR Landing And Takeoff Field Lengths. These include considerations for safety margins during landing and takeoff. Heavier aircraft require longer runways.
The longest public-use runway in the world is at Qamdo Bangda Airport in China. It has a length of 5,500 m (18,045 ft). The world's widest paved runway is at Ulyanovsk Vostochny Airport in Russia and is 105 m (344 ft) wide.
As of 2009, the CIA stated that there were approximately 44,000 "... airports or airfields recognizable from the air" around the world, including 15,095 in the US, the US having the most in the world.
Read more about this topic: Airport