Single Member Plurality Congressional Districts: The Pros, Cons, and Alternatives

By Zachariah Oquenda (CMC ’16)

While the framers of the U.S. Constitution did not create or mandate the single member plurality (SMP) system, in which voters cast a vote for one candidate only, it has remained central to the design of the U.S. electoral system for over 170 years. As David M. Farrell writes in his Electoral Systems: A Comparative Introduction, “Ultimately the main factor determining the influence an electoral system can bring to bear on a polity is the way in which it has been designed, whether in terms of the degree of electoral proportionality it produces, the type of party system it engenders, the degree of choice it offers to the voter, or other such factors.”[1] Pursuant to its design, the SMP system has created a self-perpetuating electoral disproportionality, a rigid duopolistic party system, and a false choice at the ballot, in which voters often must pick the better of two evils. If Congress could repeal its federal mandate over the electoral system, then states may be able to experiment again in electoral design, assessing the U.S.’s ability to adopt mixed electoral systems that might increase representative equality, revive competitive pluralism, and give voters more choices on the ballot.

The Apportionment Act of 1842 first wrote into law the U.S.’s current SMP system.[2] Before 1842, while some states had adopted SMPs, no such system was required. The Constitution required that representatives “be apportioned among the several States…according to their respective Numbers.”[3] The manner in which States should apportion their district and in which they should elect their representatives is not explicit in the Constitution. The year 1842 was first time Congress specified what electoral system States were to use: districts must be “composed of contiguous territory equal in number to the number of representatives to which said state may be entitled, no one district electing more than one representative.”[4]

The SMP system has its advantages and disadvantages. First, the system itself and its results are both easy to understand.[5] Out of a list of candidates on the ballot, each voter gets just one vote to pick his or her top choice. The candidate with the most votes wins. While this system is simple, the downside is that the result is proportionally unrepresentative. For example, consider a hypothetical congressional district, District X. Assume in District X that the constituency makeup is as follows: 40% of voters are Federalists, 30% are Antifederalists, and 30% are Whigs. Also assume for simplicity that these voters always vote for members of their party. It is Election Day in District X, and each party has nominated one candidate to the ballot. Under the U.S.’s SMP scheme, the Federalist candidate would win with 40%, a plurality, and because it is a single member district, the Federalist candidate represents 100% of District X’s population. This could mean that 60% of the population does not have a candidate in office that represents their views. While this example is oversimplified, the principle is clear: one can easily imagine even a majority of the population going underrepresented.

Second, SMP can produce a stable political system. When a party’s role is strictly to get representatives of the party’s interests elected to public office, political parties are inclined to concentrate power and resources so they can have more influence on the electoral process. Add to the mix that SMP provides a simple way to win a seat with only a plurality of votes. The result is a system in which political parties will tend to expand their parties’ platforms to incorporate the major issues facing the voters. When political parties are strong enough, they have the power either to ignore minority parties and their issues or (if the issue is sufficiently important to enough voters) to simply absorb the minority’s issue. This party dominance creates stability in that having fewer major parties tends to foster more predictable majoritarian legislatures.[6]

Nevertheless, the SMP system in the U.S. has tended to have the opposite effect. A duopolistic party system has so effectively marginalized minority parties that they have virtually no place at the political bargaining table, leading the countervailing powers of the two major parties into gridlock. One way to dismantle a duopoly is simply to enable other parties to compete.

While some democratic countries also rely on varieties of the plurality system, many others have adopted proportional representation (PR) schemes, or some mixture. PR systems also have advantages and disadvantages. A PR system’s goal is ensuring that any given party’s share of the districts vote is equal to the share of seats that party holds in the legislature.[7] The main differences between SMPs and PRs are (1) in the latter, voters typically must vote for their preferred party rather than their preferred individual candidate and (2) PRs by definition require more representatives per district than an SMP. For example, reimagine District X to be a PR system. Because PR systems are multi-member district (MMD) systems, let us assume for simplicity that District X will elect 10 candidates. Let the party breakdown in District X be the same as before: 40% Federalists, 30% Antifederalists, and 30% Whigs. On Election Day, each party produces a list of potential candidates that could earn a seat in the legislature, and after the voters vote with their party allegiance, 40% of the seats (4) go to the Federalist Party, 30% (3) go to the Antifederalist Party, and 30% (3) go to the Whig Party. Thus, unlike the SMP system in which 60% of the voters went unrepresented, under a PR system each voter is represented according to their share of the districts voting population.

One major obstacle to introducing a list PR system like that in District X in the U.S. is that in the U.S. has becoming increasingly “candidate-centered” rather than party-centered. Paul S. Herrnson argues that the U.S. SMP system established under the Apportionment Act of 1842 has driven the old “political machines” out of fashion and granted individual candidates “the ultimate responsibility for election outcomes.”[8] If Herrnson’s analysis is correct, then most U.S. voters today have been conditioned to relate to and connect with candidates, not parties. As Farrell points out, it is misguided to suggest that “one electoral system is ‘best’ or ‘ideal’ for all circumstances…and a judgment on which electoral system is best for a given country should be made in light of that country’s history, social composition, and political structures.”[9] What is best for the U.S.?

A single transferable vote (STV) system is likely a step in the right direction. In a STV system, voters rank their preferences for individual candidates by indicating their first choice, second choice, etc.—maximizing voters’ influence.  The STV system captures the best of both worlds between a SMP system and a PR system. The STV system minimizes the representative distortions through use of a PR-like scheme and also remains candidate-centered. According to Farrell, STV “is a system which is both proportional and which facilitates constituency politicians.”[10] In the case of our District X, parties would become secondary to the candidate-constituent relationship under a STV system. Voters select their top preferences; the candidate with the least first-rank votes is eliminated; and those votes from voters whose first-choice candidate was eliminated are “transferred” to those voters’ second choices. The process repeats until the desired number of candidates emerges. This system is more complex that an SMP, but the complexity is offset by the increased proportionality and voter choice. As for stability, evidence that suggests “proportionality produces instability is tenuous.”[11] Further research could analyze whether our political institutions could manage MMDs. While major parties are unlikely to cede power voluntarily, a STV system is conceivable in the United States.

[1] David M. Farrell, Electoral Systems: A Comparative Introduction (New York: PALGRAVE, 2001), 18.

[2] Tory Mast,, “History of Single Member Districts for Congress: Seeking Fair Representation Before PR,”

[3] Ibid., quoting Article 1, Section 2 of the U.S. Constitution.

[4] Ibid., quoting the Apportionment Act of 1842.

[5] Farrell, Electoral Systems, 20.

[6] Ibid.

[7] Andrew Reynolds and Ben Reilly, The International IDEA Handbook of Electoral System Design, (Stockholm, Sweden: International Institute for Democracy and Electoral Assistance, 1997), 19.

[8] Paul S. Herrnson, Congressional Elections: Campaigning at Home and in Washington (Los Angeles: CQ Press of SAGE Publications, Inc., 2016), 7.

[9] Farrell, Electoral Systems, 207.

[10] Ibid., 121.

[11] Ibid., 207.

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