Understanding the Factors that Affect the Incidence of Bellwether Counties: A Conditional Probability Model

AuthorBernard Grofman,Haotian Chen
Published date01 March 2023
Date01 March 2023
Subject MatterArticles
Political Research Quarterly
2023, Vol. 76(1) 119126
© The Author(s) 2022
Article reuse guidelines:
DOI: 10.1177/10659129211057601
Understanding the Factors that Affect the
Incidence of Bellwether Counties: A
Conditional Probability Model
Bernard Grofman*and Haotian Chen*
We update previous work on bellwethers in U.S. presidential elections. Comparing the most recent elections (2000-
2020) to those in earlier periods (1960-1980), we see a striking decline in the proportion of bellwe thers. We provide a
model linking this decline to conditional probability calculations that recognize that (a) a countys predictive success
likelihood varies depending upon whether the winning candidate is going to be a Democrat or going to be a Republican;
(b) as polarization rises, the number of potential bellwethers declines; and (c) election competitiveness can matter, but
closer elections do not guarantee a greater likelihood of bellwethers. Indeed, we now have very close elections but a very
low likelihood of bellwethers.
bellwether counties, presidential elections, polarization
The goal of this essay is to offer a simple formal model,
involving conditional probabilities, to explain changes in
the likelihood that we will f‌ind bellwethers, that is, po-
litical subunits (such as counties) whose votes consistently
match those of the national election in some sequence of k
elections.In particular, we wish to show why the likelihood
of f‌inding bellwether counties that match presidential
outcomes has been declining.
Tufte opens his 1975 article on bellwethers (co-
authored with Sun) with this trenchant historical quote:
Prior to the 1936 presidential election, the conventional
political wisdom had it that as Maine voted, so went the
rest of the nation. After the 46-state landslide, James
Farley, Roosevelts campaign manager, revised the the-
ory: As goes Maine, so goes Vermont.And yet, the
belief in bellwether states or counties as predictors of U.S.
presidential elections is a phoenix that is constantly being
reborn. It is as if the devastating rebuttals by Tufte (1974,
chapter 3; 1975) or the equally devastating review of the
evidence in Hopkins (2017) never happened.
Zimny-Schmitt and Harris (2020), who draw on pre-
viously identif‌ied bellwethers, look for bellwether
counties in the period 1980-2016 and identify nineteen
such. In a 7 October 2020 essay in the New York Times,
Wasserman (2020) looks to ten allegedly bellwether
counties for evidence that Donald Trump is in serious
trouble. Articles after the 2020 election examining the
predictive power of previous bellwethers are found in
other sources, including the Wall Street Journal
and the
Epoch Times.
Similar stories appeared in other recent
presidential elections. Relatedly, after the 2020 election
was over, some supporters of President Trump, such as
J.B. Shurk (23 November 2020) review the evidence of
bellwether results to argue that there must have been
electoral fraud since Biden won the presidency while
losing all but a handful of bellwether states and counties.
Why is belief in the existence of bellwether states and
counties (especially the latter) so strong? We believe that
there are two main reasons.
University of California, Irvine, CA, USA
*Grofman is Distinguished Professor of Political Science and Jack W.
Peltason Chair of Democracy Studies at the University of California,
Irvine. Chen is a PhD student in Political Science at UCI. The participation
of the authors was supported by the Peltason Chair.
Corresponding Author:
Bernard Grofman, Department Political Science, University of California
System, School of Social Sciences UCI, SSPB 2291, Irvine, CA 92697,
Email: bgtravel@uci.edu

To continue reading

Request your trial

VLEX uses login cookies to provide you with a better browsing experience. If you click on 'Accept' or continue browsing this site we consider that you accept our cookie policy. ACCEPT