The first time I spent a significant period of time in NYC, iPhones already existed. However, they didn't have much functionality to speak of. No app store, no map and no Internet underground anyway so it didn't matter. Friends told me to download a PDF in order to navigate the system. I made it through but it was daunting at times to say the least.

Because of that experience, I find this O'Reilly post from 2010 discussing an NYC Subway Map redesign very fascinating! Designer Eddie Jabbour goes into great detail about his history with subway maps, his approach to redesigning a complex system like the NYC rails and how the final Kickmap app version came to be.

I suggest you refer to the archive.org version for reading because all of the images are missing from the original post.