The Fundamental Understanding of How Elections Operate in the US


By Jennifer Nicoll Victor, Ph.D.George Mason University

Understanding the contours of how and why people vote in elections and how elections operate are fundamental to understanding how the American voting works. Holding elections and participating through voting is the defining feature of a democratic form of government. These are complicated issues, but understanding the determinants of voting, as well as how gender figures into it, can shed light on an otherwise opaque process.

An image of the US flag waving next to the Capitol.
The Median Voter Theorem helps to understand the behavior of candidates. (Image: rarrarorro/Shutterstock)

The Concept of Gender Gap

The gender gap refers to the difference between the percentage of women and the percentage of men voting for a particular candidate. Some analysts look at the gender gap by its columns and say that women preferred Clinton over Trump by 13 points, and men preferred Trump over Clinton by 11 points, so altogether, that represents a 24-point gender gap. 

But this exaggerates things. The appropriate way to measure the gender gap is by rows or in terms of a particular candidate. Men supported Trump 11 points more than women did, meaning the 2016 election had an 11-point gender gap. Over the last 40 years, women voters have supported Democratic candidates over Republican candidates by a noticeable margin. 

In every presidential election, there has been a gender gap of between 4 and 11 points where women supported Democrats more than Republicans. However, it’s important to note that much of this gap is due to the voting preferences of women of color. In fact, white women disproportionally tend to support Republican candidates over Democratic ones; however, non-white women overwhelmingly support Democratic candidates over Republicans.

This is a transcript from the video series Understanding the US Government. Watch it now, on Wondrium.

The Median Voter Theorem

In the 1940s-1950s, economists Duncan Black and Anthony Downs developed a theory that helps to understand why candidates for office and political parties seem to shift their positions in opportunistic ways. The theory is known as the Median Voter Theorem, and it’s pretty straightforward. 

An illustration of the Median Voter Theorem graph.
According to the Median Voter Theorem, voters tend to vote for the candidate who is closest to them ideologically. (Image: Colin.champion/CC BY SA/ 4.0/Public domain)

The theory holds that in an election determined by majority rules, the candidate preferred by the voter in the very middle of the spectrum will win. This is broken down into five assumptions.

First, assume that politics occurs along a continuum of left and right, and all voters and candidates can situate themselves along this line. 

Second, assume that people vote for the candidate that is closest to them along that line, regardless of which direction they are; just assume that the closer, the better. Third, assume that voters don’t play games or try to cast strategic votes of some kind, but they genuinely support the candidate closest to them. Fourth, assume there’s an odd number of voters. Finally, whoever gets the most votes wins.

Learn more about the extreme partisan polarization of current US politics.

The Implication of the Median Voter Theorem

The Median Voter Theorem shows that when the five above-noted assumptions are true, whichever voter is in the middle is the one that will win. In the case of an election, this means that whichever candidate the median voter supports will be the winning candidate. 

This Median Voter Theorem is pretty powerful. And, it turns out that it works for any distribution of voters. Suppose there are way more voters on one side of the spectrum than the other, or a polarized or a bimodal, or a perfectly normal distribution—it doesn’t matter. All of these have a median, and wherever that median lies, that is where the winning vote can be found.

The Median Voter Theorem and the Real World

Now there are a few reasons to be skeptical of how this theory works in the real world. Politics may not always fit neatly in a left-right continuum (although studies have shown that it often does). And the theory assumes that all voters vote, which everybody knows isn’t true. Still, the theory is a useful way to understand political behavior in campaigns and elections.

So, to understand the behavior of candidates in a less cynical fashion, let’s take a wider view of things. In a primary election, candidates seek to appeal to the median voter of their political party. This is fairly obvious and, however dispiriting, isn’t that surprising. 

But during a general election, candidates want to appeal to the median voter of the whole electorate for the office to which they seek election. Candidates will often adjust their campaigning or the messaging from the primary to the general election, and the median voter theorem helps understand why this happens. Nevertheless, candidates can face costs for going overboard.

Learn more about the history of political parties in the United States.

Candidate Behavior and How Elections Operate

Neighboring yard signs for George W. Bush and John Kerry in 2004 US presidential election.
George W. Bush mocked John Kerry’s campaign by sending him flip-flops. (Image: Matthew Trump/Public domain)

A candidate who dramatically shifts positions over the course of a few months will often be accused of “flip-flopping” or holding contradictory positions. Candidates are typically savvy about this and do their best to make appeals to the median voter of their electorate while also holding to individual principles, values, or ideals. 

Different candidates balance these competing goals in different ways, and some are better at it than others. During the 2004 presidential campaign, the George W. Bush campaign famously sent a box of flip-flops, the footwear people take to the beach, to the John Kerry campaign, just to razz him about having changed his positions too much.

Common Questions about the Fundamental Understanding of How Elections Operate in the US

Q: What is the gender gap?

The gender gap is among the factors that reveal how elections operate in the US. The gender gap in elections means the difference between the percentage of votes by men to women.

Q: Why was the Median Voter Theorem developed?

The Median Voter Theorem was developed to show how elections operate in the US. According to this theorem, the candidate who is in the middle will garner the majority of the electorate’s votes and win.

Q: How does the Median Voter Theorem work?

It doesn’t matter what the distribution of voters is. Every form of voter distribution has a median, and a candidate close to the median wins the election. This is how elections operate in the US.

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