Partners are more often born in different states in same-sex couples

Andrey Kamenov

Andrey Kamenov, Ph.D. Probability and Statistics

Were you and your spouse (or partner) born in the same state? It appears that five in every nine American couples can say so. Let’s take a closer look – are there states with unusually high (or low) rates? What is the percentage of same-sex couples?

As we can see from the map below, people from the Midwest and Middle Atlantic are significantly more likely to marry someone who was born in the same state.

Of course, the percentages on the map are correlated to the total population, but there are certainly other factors at play. The numbers in the Northeast are in the upper 60's to lower 70's, which is significantly higher than in the most populous state, California (52 percent), as well as Texas and Florida (the latter having one of the smallest numbers, only 41 percent).

Once we look deeper into what we can call a “couple” though, an interesting fact arises. The percentage of people born in the same state is around 2 percent higher among married couples than among unmarried partners. While small (and seemingly decreasing), the difference is still statistically significant.

The numbers for same-sex partners, however, are very different. Both partners were born in the same state in less than 40 percent of all cases, according to the data from 2009 to 2011 (the number has rebounded slightly in the recent years). Note that due to the latest data available being from 2013, we don't discriminate between married and unmarried same-sex couples, in this case, to minimize the additional error due to the difference in state laws.


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About Andrey Kamenov

Andrey Kamenov

Andrey Kamenov, Ph.D. Probability and Statistics

Andrey Kamenov is a data scientist working for Advameg Inc. His background includes teaching statistics, stochastic processes and financial mathematics in Moscow State University and working for a hedge fund. His academic interests range from statistical data analysis to optimal stopping theory. Andrey also enjoys his hobbies of photography, reading and powerlifting.

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