For years, through my NSF-funded work on the Chesapeake, I wanted a wall map of the watershed. While some exist, nothing fully encompassed the human, environmental, and modeling dimensions in a single product. The “prettier” or more artistic maps mostly stopped at the Bay's edge or left out the headwaters, and the technical ones weren't something I’d want to hang on the wall of my lab. And I didn’t want to lug one of the fancy (and expensive!) laser-cut wood ones back from Annapolis.
So I decided to make one, and it's finished (enough) to finally share.
The map shows shaded relief under an elevation tint, the full river network, the Bay and its tributaries, state lines, towns and cities, the Conowingo Dam, national parks, forests and wildlife refuges, and the named mountains and lowlands that shape where water flows. It also shows something no other map does (as far as I know): the Phase 7 land-river segments, which are the spatial units used by the Chesapeake Bay Program's watershed model to account for every BMP and bit of nutrient pollution in the basin, drawn as fine hairlines across the whole watershed. If you've ever worked with CAST’s outputs, this is what those units look like when mapped across the CBW.
One note - everything on the map was produced by R code. There is no hand-drawn step: the data are pulled from public sources (e.g., USGS, the Census Bureau, Natural Earth, the Bay Program, the Army Corps of Engineers, the National Park Service), and an R pipeline places every label, checks that nothing overlaps, and writes the files to disk. Automatically labeling is HARD to get right, and it’s certainly not perfect here. If a label couldn’t be placed cleanly, it was dropped (and if there is a collision, the R build actually fails).
Making it was a fun exercise, and affirms how programmatic cartography is advancing quite rapidly.
Get the files (both are hosted as public Dropbox links, as they’re too large for my SquareSpace tier 😀)
Poster PNG, 24 × 36 inches at 300 dpi. [link]
Vector PDF at 36 × 54 inches for large-format plotters or editing in Illustrator. [link]
The map is released under a Creative Commons Attribution 4.0 licence: use it, print it, hang it, remix it, just credit "Patrick Bitterman" and link back to this website. The R code that builds the map isn't posted in a public repo just yet - it may be eventually, but I'm glad to share it if you’d like. Just send me an email if you want to see how it works.
If you spot a misplaced name or a river I've missed, let me know. Maps are never finished, only released as new version :).