 Denver is ranked as a Beta- world city by the Globalization and World Cities Research Network . With a 2015 estimated population of 682 @,@ 545 , Denver ranks as the 19th @-@ most populous U.S. city , and with a 2 @.@ 8 % increase in 2015 , the city is also the fastest growing major city in the United States . The 10 @-@ county Denver @-@ Aurora @-@ Lakewood , CO Metropolitan Statistical Area had an estimated 2015 population of 2 @,@ 814 @,@ 330 and ranked as the 19th most populous U.S. metropolitan statistical area . The 12 @-@ city Denver @-@ Aurora , CO Combined Statistical Area had an estimated 2015 population of 3 @,@ 418 @,@ 876 , which ranks as the 16th most populous U.S. metropolitan area . 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 2015 population of 4 @,@ 757 @,@ 713 . Denver is the most populous city within a 500 @-@ mile ( 800 km ) radius , the most populous city in the Mountain West and the second @-@ most populous city in the Southwestern United States after Phoenix , Arizona . In 2016 , Denver was named the best place to live in the USA by U.S. News & World Report . 
