Even though the Tokyo-Yokohama metropolitan area boasts a population of 38 million people , it isn't the world's largest urban region by area. Every year, Demographia releases its World Urban Areas Report which features a wealth of demographic statistics on a host of cities across the world. As well as delving into the population of different cities, it also highlights the largest cities in land area.While Tokyo-Yokohama comes first in the population stakes, it comes third in land area with 3,300 square miles. The New York-New Jersey-Connecticut metro region claims the title as the largest urban area in physical size, sprawling out over 4,585 square miles.Boston-Providence comes second with 3,548 square miles. U.S. cities can't compete with booming Asian giants in terms of population but when it comes to land area, they are hard to beat. Eight of the world's ten biggest cities by land area in the United States.