Denver is ranked as a Alpha world city by the Globalization and World Cities Research Network. With an estimated population of 704,621 in 2017, Denver is the List of United States cities by population, and with a 17.41% increase since the 2010 United States Census, it has been one of the fastest-growing major cities in the United States. The 10-county Denver-Aurora-Lakewood, CO Metropolitan Statistical Area had an estimated 2017 population of 2,888,227 and is the List of Metropolitan Statistical Areas. The 12-city Denver-Aurora, CO Combined Statistical Area had an estimated 2017 population of 3,515,374 and is the List of Combined Statistical Areas. Denver is the most populous city of the 18-county Front Range Urban Corridor, an oblong urban region stretching across two states with an estimated 2017 population of 4,895,589. Denver is the most populous city within a  radius and the second-most populous city in the Mountain States after Phoenix, Arizona. In 2016, Denver was named the best place to live in the United States by U.S. News & World Report.. How many more people are in the estimated 2017 populatioon for the 12-city Denver-Aurora, CO Combined Statistical Area then the 10-county Denver-Aurora-Lakewood, CO Metropolitan Statistical Area?