John McCutcheon wrote
In looking at Tom Klinger's book Platte Canon Memories I began to wonder if runs to Waterton, South Platte, Stone Spur, Argyle, Crystal Lake, Haviland, Maddox and Altruria were run as extras. This might also include the Blackhawk Branch as well. The other question would be how often were extra run. Would there be an extra out most days in addition to thru freights or could there be multi extras. Each location is different especially considering the time of year. I don't believe Tom gave a time period when ice harvest time lasted but I would guess it was between Dec to March. One other item of note was the mine prop business, would trains be run as extras to pick up these items.
John McCutcheon
Well depends on the winter, there were some winters too warm for ice production in the Canon. December would be very early, February March would be most likely, hence the term Rush?