March of the mega-cities: World's total will rise to 37 by 2050 trends now

By 2050, it's predicted that 70 percent of the world's population will live in mega-cities, according to the Institute for Economics & Peace.

The status is typically given to a city with a population of more than 10 million - which are often beset with problems such as pollution, congestion and overcrowding. 

There are currently 33 such cities in the world, the biggest being Tokyo, with a population of 37.3 million. A total of 19 of the world's current mega-cities are located in Asia. 

Those cities will be joined by 14 others by 2050, marketing and consumer data group Statista says. Cities that will see marked growth in populations include Chicago, London and Tehran.

The biggest increase will be in Dar es Salaam in Tanzania, where the population is expected to rise from 7.5 million to 16.4 million between now and 2050.

The nation of Tanzania will account for more than half the world's population growth between now and 2050, along will fellow African nations, Ethiopia, Nigeria and Congo. 

A 2021 UN report projected the world’s population will reach around 8.5 billion in 2030, 9.7 billion in 2050 and 10.4 billion in 2100.

The same report put the current U.S population at 337 million, reaching 375 million in 2050. The population growth rate in 2021 was just 0.1 percent, the lowest since the country was founded. 

The only place in the U.S. that is expected to join the megacities ranks is Chicago, where the population is expected to balloon more than 20 percent from 8.9 million to 10.8 million. 

The Windy City will join the only other three North American cities on the list, Los Angeles, New York City and Mexico City.