The same weapon, opposite directions
Tracts sorted into ten equal groups by their firearm-suicide rate (red) and, separately, by their firearm-homicide rate (blue). Each point is the turnout-weighted mean 2020 two-party Democratic margin of that decile.
Takeaway: climb the firearm-suicide ladder and the vote dives toward Trump; climb the firearm-homicide ladder and it climbs toward Biden. One weapon, two countries.
Control for race, and only one signal is left standing
Turnout-weighted correlation of each death rate with the 2020 Democratic margin, before (hollow) and after (filled) controlling for a tract's Black population share.
Takeaway: the firearm-homicide–Democratic link collapses to zero once Black population share is held constant — it was a measure of race. The firearm-suicide–Republican link does not budge.