Guess I'll zap myself 🤩
The map is from the 2016 presidential election between Donald Trump and Hillary Rodham Clinton. The image was included in a story on the Medium website (archived here) and was used to illustrate the "Presidential winner by Congressional District." Lead Stories found it by doing a reverse image search on TinEye (archived here), an image search and recognition website.
The congressional districts marked blue voted for Clinton. The red ones voted for Trump. A screenshot of the map on Medium . com appears below:

