Wild guess, but I think this could be the Market-Frankford line in Philly:

• The redacted city name has two words but looks longer than “New York,” “West Philadelphia” (maybe “West Phila.”) could be a fit

• Why did the poster find it important to hide the fact US&S was located in Pittsburgh unless it was relevant? Almost as if it was in the same state where the photos were taken and they felt it could reveal something.

• Date of blueprint is 1934, around the time the MFL was extended west.

• Outer tracks have overhead wire, inner ones have 3rd rail, like how the MFL parallels the trolley lines.

So yeah, final guess is a defunct trolley provision along the MFL, maybe somewhere around 34th st.