Political Science 17.20
Introduction to American Politics
Professor Devin Caughey
MIT Department of Political Science
Political Geography
Lecture 20 (April 25, 2013)
1 / 15
Outline
1
Geography Matters
2
Geography Misleads
2 / 15
Outline
1
Geography Matters
2
Geography Misleads
3 / 15
Tobler’s First Law of Geography
“Everything is related to everything else, but near things are
more related than distant things.”—W. F. Tobler
Segregation: similar people forced to live together
(e.g., black ghettos)
Homophily: people choose to live near others like
themselves (e.g., hipsters in Williamsburg)
Socialization: people become more similar to those around
them (e.g., Southerner moves north and loses drawl)
4 / 15
Political Implications of Tobler’s Law
Different kinds of people (voters) are not distributed evenly
across space.
Different areas have different political leanings.
The political effects of geography are greatest
single-member district plurality (SMDP) systems
5 / 15
Example: Leftists Cluster in Cities
Across industrial societies. . .
Industrial working class concentrated in urban areas
→ economic liberalism (socialism)
Highly educated professionals attracted to urban culture
→ social liberalism (secular cosmopolitanism)
=⇒ Liberals (US Democrats) are highly concentrated in cities.
Also true of conservative-leaning groups (wealthy white
suburbs, Mormon Utah), but less extreme.
6 / 15
2012: Obama (Blue) vs. Romney (Red)
Content removed due to copyright restrictions.
To see a map illustrating the 2012 Presidential Election Results by County, go to:
http://en.wikipedia.org/wiki/File:2012nationwidecountymapshadedbypercentagewon.svg.
7 / 15
Electoral Bias: Democrats Are Inefficiently Distributed
2000 Election
40
Bush % of two−party vote: 49.7%
Districts carried by Bush: 52.4%
Number of Districts
30
20
10
0
left skew
207 Gore districts
−100 −90 −80 −70 −60 −50 −40 −30 −20 −10
228 Bush districts
0
10
20
30
District Margin for Bush Relative to Nation (%)
40
50
60
70
8 / 15
Church Attendance, by State
States of the States (Church Attendance)
Atlantic Ocean
Pacific Ocean
Gulf of Mexico
Frequency of Church Attendance :
Higher-range (45%-63%)
Mid-range (36%-44%)
Low-range (23%-35%)
Image by MIT OpenCourseWare.
9 / 15
Median Income, by State
10 / 15
Outline
1
Geography Matters
2
Geography Misleads
11 / 15
The Ecological Fallacy
The “ecological fallacy”: inferring relationships (correlations)
among individuals from relationships among geographic units.
12 / 15
The Ecological Fallacy: Immigration and Income
% Immigrant × % Wealthy, by State
Correlation across
states: +0.52
Correlation across
people: −0.05
How can this be?
13 / 15
Income and Republicanism: Individuals vs. States
Probability Voting Rop
2000
Mississippi
Ohio
0.75
Richer states vote more
Democratic (solid dots)
→ cultural differences
Richer people vote more
Republican (hollow dots)
0.50
Connecticut
0.25
-2
-1
0
1
2
Individual Income
→ economic differences
Income variation is much greater
within states than across, so
national relationship is positive.
Image by MIT OpenCourseWare.
14 / 15
Income and Republicanism: State Context Matters
2000
Probability Voting Rep
Mississippi
Ohio
0.75
0.50
0.25
Connecticut
-2
-1
0
1
Individual Income
2
Income matters more in rich
states than in poor states.
It is the rich whose voting differs
across states, not the poor,
probably because the
cultural/religious attitudes of the
rich vary more (homophily?)
Image by MIT OpenCourseWare.
15 / 15
MIT OpenCourseWare
http://ocw.mit.edu
17.20 Introduction to American Politics
Spring 2013
For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms .