Nothing Bore Fruit

Cincinnati's abandoned subway is a cautionary tale about the dangers of planning rapid transit based on corridor availability rather than demand. Admittedly, the Great Depression was an absolute reaper for in-process transit capital projects. But the fact that it was 'originally envisioned as a loop' is an immediate red flag on the 1925 planning. And.... some quality time with Google map suggested that 1925 loop was itself planned on the basis of corridor availability -- cobbling together a series of available existing railroad corridors (B&O, PRR) along with the canal path, with some handwaving on the connection through downtown.  So even if the subway segment was a good idea, the plan in which it was embedded was suspect. 

But that's not an issue specific to Cincinnati - planning from that era in general is suspect--nothing bore fruit--there were zero new rapid transit systems between 1908 and 1972 (although a few cities (Cleveland, PATCO) converted railroads or streetcars to rapid transit systems during that time).

Wiith regard to the project's continued abandonment. An amazing corridor exists, but thanks to Urban Renewal, the conditions that made it a good idea in 1925 no longer exist. 

Which is a problem. People suggest things like "Oh we have an abandoned rail line, you should add light rail" or "We had streetcar here in 1925, so you should put it here in 2025" as if land use isn't fundamental to transit feasibility.