Why this election map is so good

It manages a good balance between how turnout and vote share changed since 2016

Allow me to direct you to this piece at NPR: “How Biden Won: Ramping Up The Base And Expanding Margins In The Suburbs.”

It is a fine piece with good reporting and number crunching, but my favorite part is this map:

The colors show the change in the raw vote margin for Joe Biden and Hillary Clinton between 2016 and 2020, where bluer counties show that Democrats gained more raw votes (think a change from 100,000 to 120,000 actual ballots) and redder counties represent gains in raw votes for Donald Trump.

This is a very intuitive way to iterate on the typical swing map, which shows the change in each county’s Democratic/Republican vote share from one election to the next, but does not convey any information about turnout. But in 2020, we also care about how increasing turnout nationwide factors into the puzzle. For example, lots of counties moved slightly to the left on vote sharer, which the standard swing map would shade blue. But since turnout increased in those counties its net contribu…