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This was one of the few stretches of double track on the Santa Fe in Texas at the time. The double track started at Pampa (milepost 497 as measured from Kansas City) and ran through Amarillo to just north of Canyon (milepost 572). There were still some semaphore signals on the double track in 1974. Train symbol 811 (Extra 8711 East) passes a set of semaphore signals near St. Francis just as a cloud passes overhead.
A short time later, train symbol 138 (Extra 5550 West) goes by another set of semaphore signals. In the background is the grain elevator at Lee, TX. Pictures above are on disk 104. Steve was to my left and took the picture below about two seconds later.