Not much of a mystery where this shot was taken! In the late 1990s, after the UP/SP merger, UP assigned unique IDs to every control point on the former Rio Grande (and all of Espee). While most of the Grande trackage got an "RG" prefix (for Rio Grande), the tracks between Denver and Range got the "DS" prefix (for Denver & Salt Lake). The reason being because Tennessee Pass got the "RG" prefix, and milepost number on Tennessee Pass and the Moffat are duplicated. So the prefix was changed to avoid confusion.
Email Questions or Comments to the Webmaster.
