Every year, World Population Day is observed on July 11th, aiming to increase people's awareness of various population issues, such as the importance of urbanization, genderequality, poverty, health, and human rights. In 2025, under the theme "Empowering Youth to Build the Families They Want," the United Nations draws attention to the largest generation of young people in history, many of whom are coming of age in rapidly urbanizing contexts. Urban centers remain key to understanding these demographic patterns, as cities continue to attract populations seeking opportunity, stability, and access to essential services. Today, more than half of the global population resides in urban areas, a share projected to increase to 66% by 2050.
More than half of the world's population resides in urban areas, with over 4 billion people depending on cities as their main environment. According to the United Nations’ latest report on populations in cities, this number is expected to continue to increase over the next 50 years, prompting cities worldwide to strive to find better ways to accommodate their growing population while transitioning to more sustainable urban practices. To highlight this responsibility, the United Nations has declared July 11th the World Population Day.
Under this year’s theme, “To Leave No One Behind, Count Everyone,” the UN aims to also draw attention to the importance of data collection for reflecting societal diversity. The growth of world cities is part of this equation as an important measure for understanding global population trends. The following list presents the top 20 cities worldwide in 2024, ranked by the population size of their metropolitan areas. Comparing the results to the previous editions, the only cities to reduce their size are the two cities from Japan, Tokyo and Osaka. The highest growth rates can be observed in African mega-cities, Kinshasa and Lagos, while China continues to be the most present country in the list, with 5 metropolises present in the top 20: Shanghai, Beijing, Chongqing, Tianjin, and Guangzhou.
Half of the world’s population now lives in cities, according to UN-Habitat’s latest reports. While this number is set to increase to two-thirds by 2050, urban challenges are growing exponentially, making it more crucial than ever, to transform our cities. Annually, the world population review assesses the growth of cities and the number of residents living in metropolitan areas, to understand global evolution trends. In 2022, the list of the top 20 most populated countries remained similar to the 2021 edition, with a slight change in numbers and positions. Tokyo kept its status as the world’s largest city, with 37 million inhabitants, while Delhi and Shanghai, followed in second and third positions.
Comparing the results to the 2021 edition, the only decrease that can be seen in the top 20, involves both Japanese cities, Tokyo and Osaka. The rest of the list had, on average, a growth of 1.8% in the total of people residing in metropolitan areas. In fact, African cities Kinshasa in the Democratic Republic of Congo and Lagos in Nigeria gathered the highest rates, with respectively a 4.39% and a 3.54% increase in residents in 1 year. The largest city in the American continent is still Sao Paulo in Brazil, followed closely by Mexico City and Buenos Aires in Argentina, further down the table. In Europe, Istanbul is the most populous, with more than 14.5 million residents.
According to the United Nations’ latest report on populations in cities, by 2030, “urban areas are projected to house 60 percent of people globally and one in every three people will live in cities with at least half a million inhabitants”. Growing in both size and number, cities are hubs of government, commerce, and transportation, and in 2021, the world’s 20 largest cities are home to half a billion people. In fact, one in five people worldwide lives in a city with more than 1 million inhabitants.
Below, we have rounded up the top 20 megacities in the world of 2021, according to the number of people that live in their metropolitan area. While Tokyo is the largest city on a global level, with a total of more than 37 million residents, the majority of the most populous cities in the world are in the two most populated countries, China and India. Among these, we have 5 metropolises in China, Shanghai, Beijing, Chongqing, Tianjin, and Guangzhou, and 3 in India, Delhi, Mumbai, and Kolkata. The largest city in the American continent is Sao Paulo in Brazil with 22 million people, followed by Mexico City and Buenos Aires in Argentina. Istanbul takes the 13th position with one part of the city lying in Europe and the other part in Asia.
