sentences:  As of 2010, the region contained over 50 million people, about 17% of the U.S. population on less than 2% of the nation's land area, with a population density of approximately 1,000 people per square mile (390 people/km2), compared to the U.S. average of 80.5 per square mile 2 (31 people/km2).America 2050 projections expect the area to grow to 58.1 million people by 2025.French geographer Jean Gottmann popularized the term in his landmark 1961 study of the region, "Megalopolis