Interesting subject. I think the D&RGRy had 4 different Denver stations before the completion of Denver Union Depot in 1881. I need to review some research material which I have in storage, perhaps I can post next week in detail. A big game changer was the washout and destruction of the bridge over Cherry Creek in 1878. Bo a Google search on D&RG annual reports 1871-1883 there are some building reports and valuation.
The second D&RG station is left of the telegraph pole, beyond the Kansas Pacific passenger train, 1873.
Another view, circa 1873. Depot is right of the brick/iron smoke stack. Notice the station sign.
View showing both the D&RG depot (right) and Kansas/Denver Pacific Depot (left), 1873.
Map, 1878-79 showing layout Of Kansas/Denver Pacific passenger and freight, Denver & Rio Grande and Colorado Central depots. In 1879 the Denver, South Park & Pacific was also interchanging with the Colorado Central thus the second bridge over cherry creek (Wewatta St), the D&RG being the first being rebuilt after the flood of 1878 (Wynkoop St).