Which city is the largest?

There are many cities around the world that are “big.” A city is labeled a “megacity” if it has more than 10 million people living in it. Tokyo, Japan, ranks as the largest megacity, with 35.7 million people living in the city, according to 2012 estimates. The next biggest cities in order of size are Jakarta, Indonesia (28.0 million), Seoul, South Korea (25.6 million), Shanghai, China (25.3 million), and Mexico City, Mexico (23.2 million). In the United States New York is the largest (21.5 million), followed by Los Angeles (17.6 million). Populations of cities are constantly changing as people move in and out of them, according to the U.S. Census Bureau, a government organization that estimates how big or small cities are based on their populations, or the number of people living in them.