The USA Pro Challenge, formerly USA Pro Cycling Challenge, is quickly becoming the country's biggest stage race, this year attracting the Tour de France winner Chris Froome as part of its line-up.
Taking place at high altitudes and rife with climbing, the 2013 USA Pro Challenge begins in Aspen-Snowmass with a hilly circuit, continues to the highest point of any professional race, cresting 12,000 ft en route to Breckenridge on stage 2.
Recovery is difficult at such elevations, so the third stage will be relatively flat to Steamboat Springs. The climbers will need to save their legs for the queen stage the next day and an uphill finish to Beaver Creek village.
The 10-mile time trial in Vail will climb to 9500 feet, and will separate the true contenders from the pretenders.
Stage 6 enters new territory, heading to Colorado's Front Range for a new stage finish in Fort Collins, replete with oxygen at only 1500m elevation (4900 ft) followed by a flat and spectator-friendly finale in Denver.