With the fourth highest population density of countries and dependencies in the world at 6,300 people per square kilometer, Hong Kong is known for its shortage of residential space. Hong Kong has undergone several land reclamation projects to provide more space for residential and economical purposes, increasing its land area. This has caused the distance between Hong Kong Island and Kowloon to decrease. Hong Kong International Airport is the sole public airport in the territory, and is mostly located on reclaimed land on the island of Chep Lap Kok.