Manila, the capital of the Philippines, ranks as the city with the highest population density in the world (and some of the worst traffic congestion!). In fact, Manila spans only 24 square miles but has 1,660,714 residents, giving it a population density of 55,446 people per square mile. Metro Manila, comprising several other conjoined cities, stands at more than 12,877,000 people, making it one of the most populated metropolitan areas in the world. Most people who work in Manila, work in the production and trade of different products extiles, chemicals, coconut oil, rope, and shoes, you name it.