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The Effect of Voter Turnout on Political Polarization

I voted Credit: Jamelah E. / CC Flickr

In Brief

Voter turnout in California and across the country has been steadily declining over the past decade, especially in primary elections. At the same time, our legislators are becoming more and more ideologically entrenched, with Republicans and Democrats seemingly incapable of finding common ground. This article argues that, in part, the former causes the latter: that a restricted primary voter pool allots disproportionate influence to voters at the extreme ends of the political spectrum. We examine trends behind low voter turnout and discuss strategies to improve voter registration and turnout.

Trends in Voter Turnout: Plummeting Participation

“Voting at elections is one of the most important rights of the subject, and in a republic ought to stand foremost in the estimation of the law.”
-Alexander Hamilton, 1782

One of the founding principles of the United States is that the government derives its authority from the consent of the governed. To ensure that its agents represent the will of the people, the republic needs its citizens to demonstrate their will through the vital democratic process of voting.

This summer’s primary elections in California, however, have yet again exposed a discouraging reality in recent American politics: very few people vote. Statewide, fewer than 4.4 million people cast ballots in the June primary, setting a record low 25.2% turnout among registered voters (and a ghastly 15% of the voting-age population). These statistics embody the latest chapter in what has been a steep, decade-long decline in primary election turnout in the state (Figure 1).

Figure 1: California Primary Election Voter Turnout Figure 1: California Primary Election Voter Turnout

Nationwide, the landscape is even bleaker. In the last three non-presidential primaries (2002, 2006, and 2010), average turnout hovered near 20% of registered voters. These figures reinforce the findings of the International Institute for Democracy and Electoral Assistance, which in 2002 ranked voter turnout in the United States 138th out of 171 countries with at least some degree of voting rights, and dead last (36th of 36) among well-established democracies.For a nation that prides itself on its democratic institutions and individual liberties, we do an embarrassingly poor job in arguably the most pivotal exercise thereof: voting.

Trends in Political Polarization: The Widening Ideological Gulf

Simultaneous with this decline in voter participation, the nation has seen polarization among its elected officials surge, with the ideological gap between Democratic and Republican lawmakers widening. Over the past few decades, the number of moderate lawmakers has dwindled and politicians’ philosophies have crept more and more toward their respective poles.

Each year, the National Journal ranks every member of Congress along the political spectrum based on his or her voting record. One way the journal measures polarization is by how much the parties “overlap” on this spectrum: how many Democrats are to the right of more-liberal Republicans, and how many Republicans are to the left of more-conservative Democrats. In 1982 this was common: the ideologies of 402 of the 535 legislators overlapped with the other party at the center of the political spectrum. The parties of today’s U.S. Congress, however, share almost no common ground. Only 4 legislators overlap with the other party (Figure 2).

Figure 2: Overlapping Lawmakers Figure 2: Overlapping Lawmakers

This has led to protracted gridlock at almost every level of government. Lawmakers from either side of the aisle are simply unable to compromise. A recent study from the Brookings Institution attempted to quantify Congress’ intractability by tracking the number of “salient issues” (defined as those which the New York Times editorialized most often) left unresolved at the end of every session. The analysis concluded that gridlock has more than doubled in the past fifty years: whereas in the 1947-48, 27% of salient issues went unresolved, last year that figure reached 70%. Unless lawmakers are able to overcome their growing ideological divide, both the state and the nation will be unable to find solutions to the critical issues they face.

California’s state legislature struggles with the same problem of polarization, but unfortunately to a much greater degree. Researchers from Georgetown and Princeton Universities recently used voting records to plot the state legislators from all fifty states on an ideological left-right spectrum, and measured the distance between the average Republican and average Democrat. California had by far the largest separation between the two parties (more than twice Congress’), indicating that the state has the most ideologically polarized legislature in the country (Figure 3).

Figure 3: Ideological Distance Between Parties, State Legislatures Figure 3: Ideological Distance Between Parties, State Legislatures

A Causal Link: Low Voter Turnout Exacerbates Political Polarization

The majority of Americans are not as ideologically polarized as their representatives. A recent Pew poll found that only 21% of voting-age Americans are “consistently” liberal or conservative, while 39% reported their views as “mixed.”

So how have the country’s elected officials come to hold more polarized views than the electorate? While the majority of Americans are politically moderate, the most polarized voters go to the polls in greater numbers, especially in primaries. The smaller the voter pool becomes, the more weight a single vote carries and the easier it becomes for an active, partisan minority to determine an election’s outcome. Thus, highly-polarized politicians come to represent a moderate constituency. According to Pew, moderates vote considerably less often than staunch liberals or conservatives (Figure 4).

Figure 4: Voting Trends Based on Partisanship Figure 4: Voting Trends Based on Partisanship

The Pew poll further found that “politically-active” individuals have ideological scores that are, on average, much further from the center of the political spectrum than the average American. Their ideologies, like legislators’, have become even more polarized over the past couple decades.

It makes intuitive sense that those with the strongest ideologies show the most interest in voting. After all, they likely have the most passion for their candidates, the most defined stances on issues, and the most antipathy for the opposition. Political moderates, whose views tend to be milder and more ambivalent, often feel less compelled to vote. As a result, voters in the far wings of either party wield disproportionate influence in primary elections, nominating more polarized candidates who match their beliefs.

Primary Elections: The Birthplace of Polarization

Many believe that primaries are of relatively little consequence because only general elections actually produce final victors. It is this thinking that leads to the notoriously low voter turnout in primary election. Believing the truly significant choices all come in November, most people do not show up to vote in June and July.

This apathy can pose a serious problem in congressional elections where the constituency leans heavily towards either Republicans or Democrats. In these cases, the primary can act as the de facto general election, as the winner often coasts to an easy victory in November. Therefore, if the nominee (and eventual general election victor) is chosen by a highly-polarized, restricted primary voter pool, he or she is likely to push the government ever deeper into intransigence and gridlock.

While we have already seen that voters tend to be more ideological than non-voters, the Brookings Institution recently found that primary voters specifically tend to be more ideological than general election voters. Again, those who have the strongest views are also the most passionate about their cause and candidates, and therefore are more willing to go to the polls, even in low-attention contests.

A Boston University research team recently came to the same conclusion after surveying exit poll data and finding substantial ideological differences between primary and general election voters. In each election, self-reported ideologues constituted a significantly greater proportion of the voter pool (Table 5).

Table 5: Exit Poll Data from New Hampshire Primary and General Elections, 1996-2008


Registered Party


Primary Election (%)

General Election (%)







+ 9.57




– 11.66






+ 7.37




– 4.14






+ 11.20




– 12.06






+ 15.74




– 16.48

Taking a broader historical view, researchers from Stanford, Harvard, and Brigham Young analyzed data from every primary election for the U.S. House of Representatives between 1956 and 1998. They found that ideologically-moderate incumbents are more likely to draw primary challengers. Furthermore, moderate incumbents are more likely to lose primary elections, while those who are more ideologically extreme tend to enjoy higher margins of victory. The researchers concluded that congressional candidates face a “strategic dilemma,” wherein they can choose to please either polarized primary voters, or the more centrist general election voters – but not both. Due to the legitimate threat of being beaten by a more-ideological challenger, candidates more often choose to cater to primary voters and eventually govern with the goal of pleasing that small, polarized faction.

Seeing the Impact in Action: How Low Voter Turnout Skews Election Results

The direct impact of low voter turnout has increasingly manifested itself over the past few years, particularly in those elections featuring today’s most partisan political figures.

In 2012, then-Congressman Chris Murphy of Connecticut became the Democratic nominee for the U.S. Senate with 67% of the primary vote. He defeated Susan Bysiewicz, a more moderate former Connecticut Secretary of State. However, because voter turnout was so anemic, he was actually able to win the primary election with the support of only 3% of the state’s voting-age population.

After handily winning the general election, Murphy went to Washington, D.C. and sprinted further to the left than anyone else in Congress. The National Journal eventually named him the most liberal Senator in Washington.

Figure 6: Visualization of the Tiny Minority Who Elected Chris Murphy Figure 6: Visualization of the Tiny Minority Who Elected Chris Murphy

The same dynamic ensured the election of National Journal’s most conservative Senator, Jim Risch of Idaho. In 2008, lackluster voter turnout gave the Republican nomination to Risch with the support of less than 7.4% of the voting-age population.

Table 7: Voter Turnout in Two Senate Races


VAP in State*

Participated in Primary

Voted for Candidate

VAP Turnout*

VAP Voted for Candidate*

Chris Murphy (D., Conn.)

2.8 million





Jim Risch

(R., Idaho)

1.1 million





* VAP = Voting Age Population, i.e. those who are 18 or older

In both cases, the primary served as the de facto general election, amplifying the impact of low voter turnout. Risch won by a 24-point landslide in the general election, in a state which has not elected a Democrat to the U.S. Senate since the 1970s. Murphy coasted to a comfortable 12-point victory, as Connecticut has not elected a Republican to the U.S. Senate since the early 1980s. For both Risch and Murphy, the primary was the true test, with both candidates benefiting from abysmal voter turnout. Irrespective of political party, these examples demonstrate the polarizing impact that low voter turnout can have on the American political system.

Looking for Solutions: How Population Density Correlates to Voter Turnout

To increase turnout and reduce its impact on gridlock, we must determine why certain people choose to vote while others do not. Recent data suggests that population density may influence citizens’ voting decisions.

Examining county-by-county participation data from the 2014 California primary reveals an inverse correlation between population and turnout. Of California’s 58 counties, only the four least-populated had voter turnout rates over 50%. The smallest county, Alpine, had the highest turnout (69.6%), while the largest county, Los Angeles, had the lowest (16.3%) (Figure 8).

Figure 8: Population vs. Voter Turnout, California 2014 Primary Figure 8: Population vs. Voter Turnout, California 2014 Primary

Note: LA County, at nearly 5 million residents, is not pictured

This trend suggests that potential voters consider whether their vote will actually matter. In smaller communities, every vote can be consequential, and therefore voters feel empowered. In contrast, in communities with many thousands or millions of people, it is easy for voters to feel inconsequential or ineffectual. As one Alpine resident explained, “I feel a sense of responsibility, I feel [my vote] would be missed if I didn’t [cast it], where maybe in a larger area you feel like you get lost in the shuffle.” This sense of significance likely helped spark the high turnout in Alpine and other low-density counties.

Cost-Benefit Analysis: Why Do People Choose (Not) To Vote?

A voter’s perception of the weight of his or her vote speaks to a central theory of economic decision-making: cost-benefit analysis. Economists use an action’s relative costs and benefits to explain why we do what we do. For example, some costs of voting might be the lost time spent registering to vote, missing work, and travelling to and waiting at the polls. The benefits, on the other hand, would be the impact one might have on the outcome of an election, and perhaps a feeling of fulfilling one’s civic duty.

If voters believe the benefits of voting outweigh the costs, they will go to the polls. If not, they will stay home. To boost voter turnout, policymakers must reshape this relationship by increasing the benefits or lowering costs. It is inherently more difficult to address the “benefit” side of the equation. Convincing someone in Los Angeles that his or her single vote could determine the outcome of the election simply is unreasonable, whereas this is significantly easier to do in Alpine (there actually was an exact tie in a race for County Sheriff a few years ago).

Reducing the “cost” component is much more feasible. Everyone can recognize the effort one must expend to vote, especially if one works full-time and has other responsibilities, such as taking care of a child. Easing these costs has two potential components: increasing voter registration among eligible citizens, and increasing turnout among registered voters.

Decreasing the Costs of Voting: Boosting Registration and Vote-by-Mail

Increasing Voter Registration

There are currently 17.7 million registered voters in California, out of 24.2 million who are eligible to vote (73%). Over the past couple of years, the state has already begun a campaign to augment voter registration. In September 2012, it started allowing people to register online. Whereas mail-in registration forms take weeks to process and often fall prey to clerical error, the new online process takes only a few minutes. However, the new system’s effect on registration rates remains unclear because it is difficult to untangle the effects of online registration from other potential factors. While registration in California did increase by 942,000 (1.1%) between the 2008 and 2012 presidential elections, this followed a decade-long trend of gradually-increasing voter registration.

In September 2012 Governor Jerry Brown also signed a bill that will eventually allow individuals to register and vote the same day as the election. Twelve other states and the District of Columbia have already implemented same-day registration (SDR), leading to substantial increases in voting rates. States with SDR consistently report voter turnout that is as much as 16 points higher than non-SDR states (Figure 10). Additionally, a recent study showed that more than 10% of voters in those states did register on Election Day in 2012.

Figure 9: Turnout Rate in SDR States vs. Non-SDR States, Presidential Elections Figure 9: Turnout Rate in SDR States vs. Non-SDR States, Presidential Elections

California has not yet implemented SDR because its statewide voter database, Vote-Cal, is incomplete. This system will eventually verify that applicants are citizens and not registered to vote elsewhere. However, it is not expected to be operational until 2015, and has already experienced extensive delays.

Increasing Voter Turnout

There are a variety of policy initiatives that California could implement to encourage voter turnout. The Brookings Institution, for instance, recommended holding every primary in the country on the same day. The press could then cover it as a major news story, leaving citizens more excited to vote and more informed about the candidates.

Another practical solution is a vote-by-mail system, where every registered voter receives a ballot in the mail and must simply fill it out and send it back. The two California counties with the highest turnout in the recent primary election, Alpine (69%) and Sierra (64%), already utilize vote-by-mail.

Voting by mail greatly reduces the perceived costs of voting by eliminating the hassle of carving time out of the day to go to the polls. It has therefore drastically increased voter participation in the areas that have implemented it. Oregon has voted exclusively by mail has since the 1990s, and it consistently has one the highest voter turnout rates in the nation. A 2003 survey demonstrated that more than 30% of citizens in Oregon vote more often because of vote-by-mail. In 2000, it became the first state to conduct a presidential election by mail, and a mammoth 80% of registered voters participated, compared to less than 60% in the previous general election.

A 2010 Duke University study further demonstrated that decreasing the cost of voting through vote-by-mail leads to policy decisions that better reflects the will of the moderate general populace. As more people vote, the proportion of centrist voters increases, thus creating less incentive for politicians to appeal to polar views and a greater incentive to win over median voters. The Oregon vote-by-mail program was exceptionally effective at doing this: when vote-by-mail was first adopted in the 1995, polarization in Oregon’s legislature immediately fell (Figure 10).

Figure 10: Polarization in the Oregon and U.S. Legislatures Figure 10: Polarization in the Oregon and U.S. Legislatures

Conclusion: Action Needed to Augment Voter Turnout

Over the past decade, voter turnout in primary elections in California has halved, from 54% in 2000 to 25% this past June. Research and case studies show that when turnout is low, more-ideological candidates are chosen because the restricted voter pool allots disproportionate influence to more-ideological voters. This dynamic is especially problematic in California, which already has the most ideologically polarized state legislature in the country.

Clearly, something must be done to increase voter turnout both in California and across the country. Reforms such as vote-by-mail, online voter registration, and same-day voter registration may be effective in breaking partisan gridlock and infusing constructive compromise into our political system. To ensure that our democratically-elected leaders truly represent the views of the public, we must engage and energize the average citizen to participate actively in the civic process and vote.

Works Cited[+ Expand]

California Secretary of State,

Mike Jones, Low Primary Turnouts Mean Government by Radicals, Tulsa World, April 13, 2014,

International Institute for Democracy and Electoral Assistance, November 2000,

National Journal, The Most Divided Congress Ever, At Least Until Next Year,

Polarized We Govern?, Brookings Institution, May 2014,

Boris Shor, Georgetown University, and Nolan McCarty, Princeton University,

Boris Shor, 2014, “July 2014 Update: Aggregate Data for Ideological Mapping of American Legislatures”, doi:10.7910/DVN/26799</a> UNF:5:OVOSsr9rJl25lUk4Ck51TA== Harvard Dataverse Network.

Pew Research Center, Political Polarization in the American Public, June 12, 2014,

Elaine C. Kamarck, Increasing Turnout in Congressional Primaries, July 2014,

Juliette Miller, Demographics of Primary, Caucus, and General Election Voters, May 1, 2012,

Dacid W. Brady, Hahrie Han, and Jeremy C. Pope, Primary Elections and Candidate Ideology: Out of Step with the Primary Electorate?, Legislative Studies Quarterly, February 2007,

Connecticut Secretary of State,

National Journal, 2013 Congressional Vote Ratings,

Idaho Secretary of State,

California Secretary of State,

Seema Mehta, California’s Least-Populous County Takes Voting Seriously, June 16, 2014,

California Secretary of State,

Kathleen Miles, California Voter Registration Goes Online, Increasing Accessibility, Huffington Post, September 19, 2012,

California Secretary of State,

United States Election Project, George Mason University,

Same Day Registration, March 1, 2013,

Patrick McGreevy, Brown OKs Election-Day Voter Registration for Future Contests, LA Times, September 24, 2012,

Elaine C. Kamarck, Increasing Turnout in Congressional Primaries, July 2014,

Priscilla Southwell, Five Years Later: A Re-Assessment of Oregon’s Vote by Mail Electoral Process, the American Political Science Association, January 2004,

Oregon Secretary of State,

Justin Valasek, Turnout and Political Polarization: How Encouraging Voting Changes Political Outcomes, November 2010,

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