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As we were leaving Yuma headed east I caught a glimpse of this eastbound. I set up at Noah and caught train WCKCM (Extra 8378 East) on December 17, 1985. The train had engines 8378, 7857, 7765, and 9049.
There is not a lot of scenery in southwestern Arizona between Wellton and Gila Bend. The only spot where the hills are close to the tracks is at Mohawk. I waited at Mohawk for what seemed like an eternity. Finally the BSMFF (Extra 9376 West) came barreling through late in the afternoon. The date is November 30, 1977. Disk 55
In September 1959, the SP began work to lower the summit at Mohawk with a deep cut (21 feet) and reduce the curves from 6 degrees to 3 degrees. The job was completed in Febuary 1960. This raised the speed limit from 30mph to 50mph. You can see the original line on the left in the picture above and see how the railroad took out the curves in the satellite view from Google below. CTC was also installed at this time on the single track sections between Yuma and Gila Bend.