"Colorful Colorado" may one day need to be referred to as "Crowded Colorado," given the number of people expected to soon move here. Weld County's population is expected to double to half-a-million – and El Paso County will still be the largest county. It's not just the Front Range; A Rocky Mountain PBS I-News analysis of data from the state demographer and the U.S. Census Bureau shows seven of the 10 fastest growing counties will be on the Western Slope, including Eagle, Garfield and Routt. The numbers show an estimated 7.8 million people will call Colorado home by 2040. All that growth will take a toll on the state's infrastructure as well as water and other natural resources.