According to the Atlas Statistics on the 1932 election (
https://uselectionatlas.org/RESULTS/stats.php?year=1932&f=1&off=0&elect=0) these were the 10 counties with the highest Republican swings between 1928-1932, with the amount GOP they swung.
Iberia, LA: 21.95%
Iberville, LA: 20.34%
St. John the Baptist, LA: 16.28%
Elk, PA: 13.68%
St. James, LA: 8.69%
St. Bernard, LA: 6.68%
West Baton Rouge, LA: 5.13%
Zapata, TX: 4.21%
Jackson, LA: 3.82%
Lafourche, LA: 2.67%
(Note that these were all still Smith-Roosevelt counties despite the R swings). The Louisiana ones were all Catholic areas where Smith likely turned out many Catholic voters that Roosevelt failed to. There was also probably a group of ancestrally GOP Catholics who voted Smith due to perceived religious prejudice of the Hoovercrats but returned to their party in 1932 when religion wasn't an issue in the campaigns. Elk, PA is also a heavily Catholic area that probably shifted for the same two reasons.
The only one left is the now notorious Zapata, TX. Knowing that these South Texas counties were heavily machine-controlled at the time, the Democratic machine probably just was more effective in 1928 than in 1932. I have no idea how to otherwise explain the shift there. Considering that the county went from 89-10 GOP in 1916, to 66-34 GOP in 1920, to 60-40 DEM in 1924, to 94-6 DEM in 1928, to 92-8 DEM in 1932, this area was probably completely controlled by competing corrupt machines. None of these insane anti-bellwether swings seem natural or make clear sense otherwise.
Does anyone have access to a full list of counties that swung GOP in 1932? There can't be too many more than these 10 I imagine.
