Denver, officially the City and County of Denver, is the capital of Colorado. It's nicknamed the "Mile-High City" due to it's high elevation above sea level. According to the 2015 census, Denver, CO had a population of about 682,500 and was considered the fastest growing major city in the United States.
The city was originally established Montana City in 1858 by a group of gold prospectors. Soon after, Montana City was renamed Denver, CO. The city's location near the Rocky Mountains brought about a high population of mining and energy companies. The oil industry has been a staple in Denver, CO for decades.