Every ten years, after the decennial census and as mandated by the U.S. Constitution, states are subdivided into sets of congressional districts for representation in the U.S. House of Representatives. GovTrack provides maps of these congressional boundaries for your reference and makes the maps available for embedding on other sites. Beyond looking up the district for a specific address, maps introduce a geographic context that tells us about the demographics and rural/urban nature of a district, as well as whether that district's boundaries show signs of gerrymandering.
Recently, we redesigned GovTrack's map of congressional districts to be more responsive, more legible, and easier to reproduce. To create these maps, we used data from the U.S. Census Bureau, a few cartographic tricks and tools, and web map hosting from Mapbox. I'll explain the process here, and you can reference the exact workflow [on GitHub](https://github.com/aaron