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Why Marrying Someone Like Yourself Is Bad For America

The Economist recently ran a story with the provocative subtitle “How sexual equality increases the gap between rich and poor households.” The story is about an economics paper titled “Marry Your Like: Assortative Mating and Income Inequality.” The paper argues that because educated, high-income people tend to marry each other, this concentration of wealth has increased income inequality between 1960 and 2005. Before you start to object, let’s break down what the paper says:

  1. More women are in the labor force, more women have college degrees and wives contribute more to household earnings than they did in 1960.
  2. The share of income generated by wives increases as families get richer. The authors note, looking at data from 1960 and 2005, that “at the 80th [household income] percentile the share that married woman provided to household income rose from 16 to 34 percent, and from 13 to 25 percent at the 20th [household income] percentile.”
  3. Random matching would decrease inequality in 2005 but not in 1960. A number known as the Gini coefficient is used to measure national income inequality, with a lower number indicating less inequality. The authors ran an experiment to simulate random matching of spouses. This random matching leaves the 1960 Gini coefficient mostly unchanged while lowering the 2005 number from 0.43 to 0.34. This suggests that there is more assortative mating happening today.

Slate’s Matt Yglesias notes that the results of this paper have to be put in context. As discussed, more women are going to college and entering the workforce. Evidence suggests there has always been assortative mating, but the limited number of working, college-educated women made assortative mating impractical for much of the population until recently. The authors of the paper find that returning women to 1960 levels of labor force participation would actually increase inequality. Yglesias goes on to say that “on a public policy level, there’s no reasonable way to discourage these trends,” and this aspect of inequality has resulted from things we consider positive changes: more women working and earning degrees, and more economic benefit from having a degree.

While this study might not have immediate policy application, it’s interesting in the context of what has been labeled the “Big Sort,” after a 2008 book by Bill Bishop. Bishop makes the case that where Americans choose to live is increasingly dictated not only by economic reasons, but also by a desire to be near people who share their “lifestyle and beliefs.” From a New York Times article about the book:

Bishop argues that this clustering of like with like accelerated in the tumult of the 1960s when, unmoored from the organizations and traditions that had guided their choices about how to live, Americans grew anxious and disoriented — and reflexively sought comfort in the familiar, cocooning themselves in communities of people like themselves.

This sorting, according to Bishop’s argument, leads to increasingly extreme, self-reinforcing belief systems, which explains our current political polarization.

Not so fast, say researchers Samuel Abrams and Morris Fiorina. In “The Myth of the ‘Big Sort’,” they poke holes in Bishop’s methodology. They argue that looking at presidential election margins, as Bishop does, is less methodologically sound than using voter registration. Abrams and Fiorina find little evidence that there are more “landslide counties” – an approach Bishop used to show that increasingly large margins of victories in some counties indicate political sorting. The researchers present data indicating that more people are registering as independents than was the case in the 1970s. They also point to research that says that suburban neighbors are increasingly isolated from each other and rarely talk politics.

In their article and in other research, Abrams and Fiorina do recognize that some sorting is happening. Political parties have become more homogenous over the last 50 years, mostly as conservative Southern Democrats have become Republicans. The researchers also conclude that political elites have become more polarized, although they dispute how much of an effect this has had on public opinion.

Are we experiencing a “Big Sort”? Maybe, although the case of geographic sorting may be overstated. Divisions between North and South, urban and rural, have been a feature of this country since its founding. Abrams and Fiorina hint at a different method of sorting: “Advances in communications technology have made geographic location less important than in earlier eras.” The fragmentation of media lets us consume news and commentary we’re predisposed to agree with. Much more public information exists about potential friends, future employers, or products we might like to buy. We don’t need to move to a different town to surround ourselves with people and things that fit comfortably with our preexisting beliefs.

What’s this have to do with assortative mating? It’s most likely that the proximity of people of similar economic and educational attainment (e.g. college graduates mostly working with other college graduates), combined with more college-educated women in the workforce, has lead to a rise in assortative mating. But technology allows people to find partners who are just like them, politically, economically or in other ways. Some research suggests that people find potential dates with similar political views more desirable.

Is it possible that by celebrating our diversity, and by putting more of ourselves online, we are providing the tools to sort ourselves into homogenous groups? Regardless, as Yglesias writes, it’s not feasible or ethical to discourage most of these trends. But this does fill in the picture of an America that seems more politically polarized, and is empirically experiencing greater disparities in income. Even if we don’t want to treat the causes, maybe we can alleviate the symptoms. But what if we’re too divided to agree on the public policy steps that should be taken?

About the Author

Matt is a native Rhode Islander and a recent graduate of Brown with a bachelor's degree in history. After spending the last three years living in Boston and working at Harvard Law School, he returned to Brown to pursue a master's degree in public policy. When not inundated with schoolwork, Matt likes to relax with a Red Sox game, some Miles Davis, or a Sherlock Holmes mystery.