The Chesapeake Bay watershed, rendered as an urban transit network. This is probably the most-requested map I’ve had since I launched the series; I hope you will enjoy it.
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somethingaboutmaps 
this is absolutely amazing, and i hate to be a nitpicker, but how about some rivers on the east side of the bay?
i think you could add the elk, chester, choptank, nanticoke, and wicomico.
just a thought. regardless, this is pretty badass!
Also, should this include the Occoquan?
Second IMGoph’s sentiment – this is amazing. Great job.
This is great! One question–why isn’t the Anacostia included?
I can’t speak to the very specific thought process I had at the time, but it was probably not included in the data set I used. There are literally thousands of streams in the area, and there’s not room to fit them all, so I had to make some decisions on which were the most significant in length. In this case, I used a data set from the federal government which eliminated the smaller features to make those decisions.
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Great maps! I’m also wondering about the Anacostia. And the branches of the Potomac. Shouldn’t they be labeled? All in all, though, a wonderful and useful schematic. Thank you!
Thanks for the kind words. Though locally significant, the Anacostia is a pretty short river. The label for “Washington,” for example, is bigger than the entire river’s length on a map like this. It would seem out of place, I think, to include something that small at this scale, especially while leaving off the hundreds of rivers longer than the Anacostia.
As to the Potomac, I thought for a time about how to treat the various branches, which all have lengthy official names such as “North Fork South Branch Potomac River.” Through the series, I decided to just keep the labeling scheme fairly minimalistic as a style decision (and a space decision), by stripping all those sorts of qualifiers and just retaining the base name.
Love this!