Derrick is "Archivist for the Bronx County Historical Society". Well, or was when this was published in 2001 by New York University Press. Copyright appears to be held by "The History of New York City Project, Inc."
A little over 250 pages of text in an over 400 page volume (the balance in bibliography AND notes and an index), Derrick's focus is on _policy_, and how the Dual System came to create the rapid transit system that continues to serve NYC well. Derrick ignores the larger financial background (does the 1907 panic merit even a passing mention? No, it does not. Which is pretty incredible, all things considered) and quite a lot of other things as well. However, I think he is justified in doing so, because otherwise this thing would have gotten way out of control.
In a lot of ways, this is the story of McAneny engaging in a deliberate negotiation with various newspaper interests, the IRT (the company which ran the first subway), Brooklyn Rapid Transit and the various NYC commissions attempting to create a big enough rapid transit system to empty out the overpacked communities of lower Manhattan and just-over-the-bridges. The goal was a virtuous one, and by no means inevitable in its success, which makes this a very suspenseful read even if you know how it turns out.
If you find long-running, seemingly fruitless, multi-way negotiations exasperating, this book might help teach you the benefits of persistence. Alternatively, it might make you want to destroy the book. Hard to say.
I enjoyed it, but I think it might have made more sense if I knew more about Tammany Hall. I have a book upstairs about that, too. I'll get to it, but first, I'll read _Down the Asphalt Path_.