BPEA | Fall 2012

Political Polarization and the Dynamics of Political Language: Evidence from 130 Years of Partisan Speech

Laurence Wilse-Samson,
Laurence Wilse-Samson Columbia University
Ethan Kaplan,
Ethan Kaplan University of Maryland at College Park
Jacob Jensen, and
Jacob Jensen Stanford University
Suresh Naidu
Suresh Naidu Columbia University

Fall 2012

We use the digitized Congressional Record and the Google
Ngrams corpus to study the polarization of political discourse and the diffusion
of political language since 1873. We statistically identify highly partisan
phrases from the Congressional Record and then use these to impute partisanship
and political polarization to the Google Books corpus between 1873 and
2000. We find that although political discourse expressed in books did become
more polarized in the late 1990s, polarization remained low relative to the late
19th and much of the 20th century. We also find that polarization of discourse in
books predicts legislative gridlock, but polarization of congressional language
does not. Using a dynamic panel data set of phrases, we find that polarized
phrases increase in frequency in Google Books before their use increases in
congressional speech. Our evidence is consistent with an autonomous effect of
elite discourse on congressional speech and legislative gridlock, but this effect
is not large enough to drive the recent increase in congressional polarization.