 Colorado's population had expanded from 3.1 million at the beginning of the 1990s to over 4 million by the end, and Denver closed out the decade with more than 554,000 people.With Denver experiencing so much growth, the large scale transportation projects undertaken by the Regional Transportation District under the leadership of Clarence Marsella, needed to be successful.Fortunately, T-REX was completed in November 2006, 22 months ahead of schedule.