Here’s something a bit different, just for kicks. These extremely abstracted topological diagrams of U.S. rail transit systems were sent to me by Herbie Markwort, who runs the Gateway Streets blog about transportation issues in St. Louis.

Personally, I love the way that these diagrams look. Simplified down to their bare essentials – connecting points and termini – the systems take on an almost runic appearance. As much as possible, the distance between connection points is kept the same in these diagrams, regardless of the length of the lines in real life.

Obviously then, diagram “A” could represent any of the single-line rail systems in the U.S. – Buffalo, Phoenix, Seattle, et al – and diagram “B” represents a system (or systems) with just one branch line extending from a main trunk line. It’s certainly a fascinating way to look at something familiar from a different viewpoint, and had me scratching my head for quite a while before Herbie let me in on the answers.

Let me know what you think they are by commenting below. Any guesses?