It entered service for the Milwaukee Road on July 14, 1965 as locomotive number 388. By the end of the month, it was pulling freight across the system. The first documented trip in Washington we have identified occurred on July 31, about two weeks after it entered service.
According to this train sheet, the 388 passed Maple Valley, WA at 12:23 a.m. pulling 2,915 tons (25 loads and 58 empty cars) with three other U25B locomotives. It then passed Black River at 12:50 a.m. on the way to Tacoma. It would have passed through Cle Elum sometime on July 30.
Here is an August 1965 view of the 388 going through Cle Elum, one of the earliest pictures of the locomotive. Right behind the power, all GE U25B locomotives like the 388, the dynamometer car is collecting data on the performance of these new additions to the fleet.
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