Migration and Sorting in the American Electorate: Evidence From the 2006 Cooperative Congressional Election Study

• Author: Ian McDonald
• Published date: 01 May 2011
• Date: 01 May 2011
• DOI: http://doi.org/10.1177/1532673X10396303
• Subject Matter: Articles

American Politics Research

39(3) 512 –533

© The Author(s) 2011

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DOI: 10.1177/1532673X10396303

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396303APR

1Portland State University, Portland, OR

Corresponding Author:

Ian McDonald, Hatfield School of Government, Division of Political Science, Portland State

University, Box 751, Portland, OR 97207

Email: irm@pdx.edu

Migration and Sorting

in the American

Electorate: Evidence

From the 2006

Cooperative

Congressional

Election Study

Ian McDonald1

Abstract

Migration is a significant factor in the composition of U.S. electoral constituen-

cies, including U.S. House districts. Does migration contribute to geographic

homogeneity, and does the result contribute to political polarization in a sig-

nificant way? This article considers this question using the 2006 Cooperative

Congressional Election Survey. To determine individual-level migration pat-

terns, residence information from individual survey respondents is matched

to the U.S. Postal Service’s change of address database. This technique pro-

vides precise information about respondents’ migration history that follows

the preferences expressed in each individual’s survey response. I find sup-

port for the claim that migrants are more likely to move into a congressional

district that matches their ideological preferences even after controlling for

the partisanship in the district of origin. This result emerges for both major

parties in two sets of model specifications: multinomial logit models restricted

to migrants and a selection model that includes all respondents.

McDonald 513

Keywords

internal migration, sorting, political polarization, political ideology, residential

mobility

Introduction

When does domestic migration contribute to the clustering of political pref-

erences in the United States? The process that links migration to clustering,

and its potential significance, is simple and intuitive. Given the right condi-

tions, migration can reconfigure electoral constituencies by consolidating

individuals with shared preferences into closer proximity, both locally and

nationally, even if individual preferences remain unchanged. Migration can

also change every relevant consideration about the social context and its effect

on preferences and behavior. This possibility has special significance in the

United States, thanks to its geographic diversity and the enormous array of

communities and single-member electoral districts throughout its majoritarian

legislative systems.

Residential mobility is a defining characteristic of the American experience,

and Americans generally regard changing residences as easy and unremark-

able. But the flow of internal migration in the United States is steady and its

effects are cumulative. The 2000 census reports that 31.6% of all native-born

Americans now reside in a state that does not include their birthplace. Although

the rates have declined slightly in recent years, the percentage of all Americans

who move to a new state has never fallen below 2% in any single year from

1947 to 2006, while the annual percentage of residents moving between coun-

ties has never dropped below 7.9%.

To understand the effects of migration, changes in both the composition

and size in any given location must be taken into account, even if we suppose

that political preferences of migrants persist from one place to another. Factors

that change aggregated political preferences cited in the domestic migration

literature are well documented and include individual wealth, age, job prospects,

family status, ethnicity, and variables that can be generalized as matters of

taste (Emerson, Chai, & Yancey, 2001; Massey & Denton, 1993). This com-

plexity is further compounded to the extent that the factors are shaped, though

not completely defined, by the ongoing migration decisions of other people.

An important body research in political behavior has considered the possibil-

ity that migration patterns in recent decades has lead to self-segregation that,

in turn, homogenizes electoral constituencies and contributes to increased