Iowa caucus bellwether counties

[Nym90]

The following counties have backed the winning candidate in every Democratic caucus since 1992 (at least; that's as far back as we have county maps on Atlas; if you know of county results from before then, feel free to expand this list):

Allamakee
Audubon
Black Hawk
Bremer
Buchanan
Buena Vista
Carroll
Cedar
Clayton
Clinton
Des Moines
Dickinson
Dubuque
Grundy
Iowa
Linn
Marshall
Muscatine
Plymouth (tied in 2000)
Poweshiek
Scott
Story
Webster
Wright (tied in 2004)

And these counties have voted for the winning Republican in every Iowa caucus since 1992:

Adair
Appanoose
Audubon
Benton
Buchanan
Butler
Cass
Cherokee
Clay
Crawford
Davis
Emmet
Gayette
Floyd
Franklin
Greene
Grundy
Guthrie
Henry
Jasper
Kossuth
Louisa (tied in 2012)
Madison
Mills
Page
Ringgold
Sac
Wapello
Warren
Wayne
Wright

[RI]

(at least; that's as far back as we have county maps on Atlas; if you know of county results from before then, feel free to expand this list):

I have a thread for that: https://uselectionatlas.org/FORUM/index.php?topic=97330.0

Going back to 1988 for the Dems reduces the list to:

Buchanan
Buena Vista
Carroll
Clayton
Clinton
Dubuque
Grundy
Marshall
Muscatine
Plymouth
Webster
Wright

1984 and 1980 don't eliminate any of them. I don't have complete data for 1976 and before.

For the Republicans, 1988 only eliminates three or so. Going back to 1980 eliminates a lot, leaving:

Benton
Cherokee
Clay
Crawford
Franklin
Greene
Sac
Warren

Data from prior to 1980 is not available.

[RI]

Map:

[Nym90]

Thanks. Interesting how the bellwether counties for both parties run essentially east to west down the middle of the state.

[Vern]

How many Counties are left now as bellwethers?

[Penelope]

How many Counties are left now as bellwethers?

If no counties switch away from Cruz, or to Cruz as the last few results come in:

Benton
Crawford
Franklin
Warren