Here's a nice little archived slide from my dad's collection, taken August, 1967. The photographer is unknown, but it was taken from a vestibule window from an eastbound UP passenger train. From the March 10, 1968 UP timetable, the train may have been Train 104, due eastbound through San Bernardino at 15:57, which would put passenger trains near Summit about an 45 minutes to an hour later. But the lighting looks more late morning than late afternoon to me. This could have been a fantrip, or there may have been a different train or schedule from that earlier date.

The Santa Fe train is most likely the Chief, apprently running late, as it was typically due westbound at San Bernardino around 06:50. Comments always welcome, especially regarding train/timetable info for this picture.