^ b. Area of the Federal District that includes non-urban areas at the south
Mexico City (Spanish: Ciudad de México; abbreviated CDMX) is the capital and largest city of Mexico. It is the most populous city in the Western Hemisphere and the second most populous city in the world (after Tokyo). It is also one of the polluted cities in the world. The Aztec people were here before the Spanish came and founded Mexico City. It was refounded in 1521 by Hernán Cortés. Today, about 8.5 million people live in the city, and about 18 million live in the Greater Mexico City urban area. The city of Mexico City ceased to exist in 1928. Since then, there is only the Federal District.
Mexico City has 18.1 million people. It is the city with the second highest number of people in the world after Tokyo in Japan and just slightly more populated than Mumbai in India.[9]
↑"Largest Cities of the World - by population". worldatlas.com. Retrieved 2008-10-22. Including population within the recognized metro area of the city and also people living in the immediate surrounding area outside of the established border of the city the most populated cities in the world are: 1. Tokyo, Japan - 28,025,000, 2. Mexico City - 18,131,000, 3. Mumbai, India - 18,042,000, 4. São Paulo, Brazil - 17, 711,000, 5. New York City, USA - 16,626,000.