With over 37 million residents, Greater Tokyo is the most populous metro area in the world today. Urban growth is not unique to Japan. By 2030, the United Nations predicts that the world will have 43 megacities, defined as metro areas with more than 10 million people. Most of them will be in developing regions in the Middle East, Asia, and Africa. The UN recently released its annual World Urbanization Prospects, which estimates which metro areas will have the highest populations by 2030. On World Population Day this Wednesday, let's take a look at the top 13: 13. Greater New...