1. Urbanization has increased dramatically over the last 200 years as the number of people living in urban areas and the land occupied by cities has grown.
2. In 1800, only 2 cities had over 1 million residents but by 2000 that number had grown to 311 cities as populations shifted from rural to urban areas.
3. The distribution of the largest cities has also changed significantly over time, with Asia growing to dominate the list of the top 100 largest cities in 2000 after previously being led by Europe and North America in 1900.