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New Yorker or Angeleno? Your tweets reveal which city you belong to

The Big Apple versus The Big Orange. The City of Dreams versus The City of Angels. I’m referring, of course, to the ongoing rivalry between New York City and Los Angeles. Hilarious “survey” videos and talk shows will give you one picture of the cities. My colleagues and I decided to take a more serious look at the differences between the cities, so we studied what everyone else was talking about – on Twitter.

We set out to answer a simple research question: Are people who are located near each other likely to tweet about similar things? To do so, we analyzed millions of GPS-enabled tweets across New York City and LA. This type of study – looking at huge amounts of social media traffic by location – is useful for more than tracking pop culture memes in different cities. It could be valuable for understanding many aspects of urban life, including the effects of the COVID-19 pandemic.

If we were considering the case of a single, small community that takes pride in local events, celebrities and culture, the answer to our research question would be a resounding “yes.” One challenge in comparing two large, international cities is the reality that globalization has led to unprecedented interaction among multiple cultures and peoples, along with Starbucks and McDonald’s seemingly in every city on the planet.

For cities that are international but also take pride in their uniqueness, the key is teasing out the extent to which local qualities or global culture dominate tweeting behavior. We designed our methods to be precise enough to account for the fact that, contrary to the fun videos, New York City and LA are quite similar. Both have high housing costs, famous educational institutions, hospitals, museums and other cultural establishments, and residents who tend to vote Democratic.

Define ‘close’ and ‘same’

Our study tackled two problems: There’s no simple definition of “close together,” and it’s difficult to say whether two tweets are about the same topic. We combined several definitions of “close together,” ranging from people located in the same city to the distance in miles between their coordinates, using a common formula from spatial sciences.