After Union Pacific merged Southern Pacific, it continued to operate a Z train between Denver and Salt Lake City over the Moffat Line for several years before eventually moving it to the Overland Route through Wyoming. On July 8, 2000, The eastbound Z train descends the front range at the west switch of Clay siding, led by Cotton Belt GP60 No. 9667 and UP SD40-2 No. 3083, a former Chicago & North Western locomotive.
