This is really, really cool: an animated NYC subway map, with the lines and stations appearing in the order in which they were built. It’s amazing to me that the West Side IRT — what are now known as the 1/2/3 lines — were built way before lines in lower Manhattan, at a time when lower Manhattan probably had a crushingly greater need for a subway line; it wasn’t until later that the IRT was extended down into the lower reaches of the island. (It’s also cool that two lines in Brooklyn started it all.)