At Speer, Wyoming, just west of Cheyenne, where the Denver line divides from the Overland Route. Here in 2005, I'm guessing it is still there. There was another tank at Granite, Wyoming also, a bit further west, well into the 1990s, but not sure if it still is.

http://naphotos.nerail.org/showpic/?pho ... e=340&key=