The 10 Most Populous Cities in the World

The population of São Paulo in 2021 is estimated at 22,237,472. In 1950, the population was just 2,334,038. Since 2015, São Paulo's population has grown by 194,444, with an annual growth rate of 0.88%. These population estimates are based on the latest revision of the UN's World Urbanization Prospects.

São Paulo is the most populous city in Brazil, the largest in the Americas, and in the Southern Hemisphere. It is also one of the top 10 largest urban areas in the world. São Paulo is a global city with significant influence in arts, entertainment, finance, and commerce. Additionally, it hosts the largest LGBTQ+ pride parade in the world. The city is known for its large immigrant population, with a survey by the University of São Paulo showing that “81% of students report being descendants of immigrants”.

Mexico City is one of the most populous and densely populated cities in the world. As of 2021, its population is estimated at 21,918,936. In fact, 20% of Mexico's total population lives in Mexico City. Rapid growth has led to challenges in providing essential services, such as housing, but there is still hope for the future. The population grew by only 0.5% from 2019 to 2020.

Mexico City has a rich, long history and is known as one of the largest financial centers in Latin America and the largest Spanish-speaking city in the world. Today, Mexico City is home to a large number of immigrants and foreigners from Canada, the United States, South America (particularly Colombia and Argentina), Central America (notably Guatemala and El Salvador), the Caribbean (mainly Cuba and Haiti), Europe (especially Spain and Germany), and the Middle East (including Egypt, Syria, and Lebanon). More recently, there has been a wave of immigration from the Asia-Pacific region, including South Korea and China.

In 1950, the population of Dhaka was just 335,760. Today, it has become one of the most populous cities in the world, with an estimated population of 21,741,090. Dhaka is a vibrant city located in central Bangladesh along the Buriganga River. It is not only the capital but also the largest city in the country. In 2016, the Greater Dhaka Area had a population of 18.237 million.

The population density in Dhaka is an astonishing 23,000 people per square kilometer. Around 2,000 people move to the city each day, often fleeing from natural disasters or disease outbreaks in rural areas. It's no surprise that a quarter of Bangladesh's population lives below the poverty line, with an estimated 3 million people residing in slums within Dhaka.

The capital city of Egypt has been settled at least since the 4th century, due to its strategic location along the Nile River. Despite medieval plagues and riots that devastated the city in the 1950s, Cairo grew at a rapid pace. In 1950, Cairo's population was 2,493,514. Today, that number has surpassed 20 million, with an estimated population of 21,322,700. Even the city's core population is remarkably high – 12 million people.

Cairo is the largest city in both Africa and the Middle East. Nearly 100% of Egypt’s population lives in Cairo, Alexandria, or other locations along the Nile River and the Suez Canal. Cairo and its larger metropolitan areas have some of the highest population densities in the world, with a population density of 19,376 people per square kilometer, ranking it 37th in the world.

It would be incomplete not to include the cities of the world’s most populous country in this list. In 1950, Beijing had a population of 1,671,365. Today, Beijing is the second-largest city in China and one of the most populous in the world, with an estimated population of 20,896,800, almost the entire population of Australia.

The population of Beijing has been growing at a rapid pace. Census data from 2000 and 2010 show that the city’s population increased by 44%, from 13,569,194 in 2000 to 19,612,368 in 2010. It is projected to continue growing through 2035.

According to Reuters, one of the major challenges of such a large urban population is pollution. Beijing suffers from some of the worst air quality in the world, primarily due to coal-fired factories and heavy traffic congestion.

Another Indian city makes it to the list of the world’s most populous cities—Mumbai, also known as Bombay, the capital of Maharashtra. Its trains alone carry about 6 million people every day.

The population of Mumbai has grown over the past two decades and is currently estimated to be 20,667,600. In fact, its population has doubled since 1991, when rural migrants flocked to the city in search of jobs. However, this growth has also brought significant challenges. According to a report by World Population Review, 41% of Mumbai’s residents live in slums. The rapid expansion has led to serious health and infrastructure issues that the government must address.

Osaka is another Japanese city that ranks among the world’s most populous. In 1950, its population was 7,005,284. Surprisingly, the population of Osaka did not increase in 2021 compared to 2020—in fact, it decreased. The current population is estimated at around 19,110,600.

The decrease is calculated at -0.29%. In 2020, Osaka’s population was 19,165,340, dropping to 19,110,600 by 2021. This decline is attributed to residents moving from the city center to the suburbs. Factors such as a low birth rate and a higher number of deaths than births, approximately 200,000 more deaths, have contributed to this trend.

Tokyo's population in 2021 is estimated to be 37,435,191. In 1950, the city had 11,274,641 residents. Since 2015, Tokyo has seen a population decline of 53,324 people, equating to an annual change of -0.14%. These estimates and forecasts come from the latest revisions of the United Nations' World Urbanization Prospects, representing the metropolitan area of Tokyo, which includes the city and surrounding suburban regions.

Tokyo has always been the largest city in Japan and is one of the most powerful cities in Asia. Formerly known as Edo, it grew from a small village and by 1720 became the first city in Asia to exceed a population of 1 million. The migration from rural areas to urban centers, alongside international immigration, has helped make Tokyo the most populous city in the world. Tokyo is also consistently ranked as one of the wealthiest cities globally.

Delhi, also known as the National Capital Territory (NCT) of India, is one of the largest urban areas in the country. It is the most populous city in India and the second most populous in the world. As of 2021, Delhi's population is estimated at 31,181,376, a significant increase from just 1,369,369 people in 1950. Since 2015, the population has grown by 890,440, marking an annual growth rate of 2.94%. These population estimates are based on the latest revisions from the United Nations' World Urbanization Prospects, which include Delhi along with its surrounding suburban areas.

Delhi has been continuously inhabited since at least the 6th century, and it has served as the capital of numerous empires and kingdoms throughout history. It has also been destroyed and rebuilt several times. Delhi is home to Indraprastha, the mythical capital of the Pandavas, and it became a major trade route connecting the Gangetic plains with northwest India during the reign of the Delhi Sultanate. In 1639, Shahjahanabad, a walled city, was built as the capital of the Mughal Empire and remained so until 1857. Today, Shahjahanabad is part of Old Delhi. In 1911, the British decided to move India's capital from Calcutta to Delhi, and New Delhi was constructed in 1912 to the south of the old city. Today, New Delhi is a part of the larger Delhi metropolitan area and serves as the capital of India.

Shanghai is the largest city in the world by land area. It is also one of the most populous cities globally and has experienced some of the fastest urban growth in the past two decades. According to the World Population Review, Shanghai has maintained a nearly double-digit growth rate every year since 1992, except during the global recession of 2008-2009.

Despite a slight slowdown in growth, the city continues to expand rapidly. Experts predict that Shanghai's population could reach 50 million by 2050. Currently, Shanghai's population is estimated at around 27,795,702 people. The city covers an area of 6,340.5 square kilometers (2,448 square miles), mostly flat, with only a few hills in the southwest and an average elevation of just 4 meters. Shanghai is also crisscrossed by a vast network of rivers, canals, lakes, and streams, all of which create the perfect environment to support a large population.