The world's population is growing rapidly and reached 7.3 billion people in 2011. The highest rates of population growth are occurring in low income countries (LICs), such as Zimbabwe, Malawi and Niger. Some countries are experiencing population decline, for example Japan, Russia and Ukraine.
Today more than 50% of the world's population live in urban areas. The number of cities with over 10 million people is increasing. These are called megacities. There are now 34 megacities in the world. The table shows the top 10 megacities.
|Rank||Urban area||Country||Population estimate|
|9||New York||United States||20,630,000|
(Demographia World Urban areas 2015)
The population of cities usually changes in one of two ways:
More and more people are leaving rural areas and moving to cities. This is called rural to urban migration. People move because of push and pull factors. Push factors are things that make people want to leave rural areas and pull factors are the things that attract people to the city.