In the 7000s BC, the largest human settlement was located in the ancient Near East. Cities have continued to grow over the centuries. 200 years BC, Alexandria already had 1,000,000 inhabitants. A few centuries later, Rome became the most populous city in the world.
In 2010, Tokyo, Japan held the title for the largest city in the world with a population of 36 million people. According to predictions, Tokyo’s city population is not expected to rank among the top 20 cities in the world. Interestingly, it is estimated that only six out of the top 20 cities with the highest population in 2010 will still remain in the top 20 by the year 2100.
Today the top 10 biggest cities by population are:

  1. Tokyo, Japan – 36,834,000
  2. Delhi, India – 21,935,000
  3. Mexico City, Mexico – 20,132,000
  4. Shanghai, China – 19,980,000
  5. São Paulo, Brazil – 19,660,000
  6. Osaka, Japan – 19,492,000
  7. Mumbai, India – 19,422,000
  8. New York, United States of America – 18,365,000
  9. Cairo, Egypt – 16,899,000
  10. Beijing, China – 16,190,000

In 2050 the world will see a boom in Lagos, Nigeria’s larger city, driven by local and global migration. Mumbai is expected have a population reaching 42.5 million.
According to projections made by Hoornweg & Pope the world’s 10 largest cities in 2100 will be:

  1. Lagos, Nigeria – 88,344,661
  2. Kinshasa, Democratic Republic of Congo – 83,493,793
  3. Dar Es Salaam, United Republic of Tanzania – 73,678,022
  4. Mumbai, India – 67,239,804
  5. Delhi, India – 57,334,134
  6. Khartoum, Sudan – 56,594,472
  7. Niamey, Niger – 56,149,130
  8. Dhaka, Bangladesh – 54,249,845
  9. Kolkata, India – 52,395,315
  10. Kabul, Afghanistan – 50,269,659
    However these are only projections even if they come from extremely competent analysts.
    The total urban populations for all nations are indeed influenced by the scale of natural increase in populations. However, whether the population growth rates used in estimating city populations will be sustained is a complex issue. It depends on various factors such as fertility rates, mortality rates, migration patterns, and government policies. These factors can change over time and have a significant impact on population growth rates. It’s difficult to predict with certainty whether the growth rates will be sustained in the long term.
    (Source: Wikipedia/iied/Born to Engineer – Image: Lagos, Victoria Island/Kadara Enyeasi)