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Mapping Gang Turf

A new paper from P. Jeffrey Brantingham, an anthropologist at UCLA, uses a mathematical model for hunting to map street gang territory. From the UCLA Pressroom:

“The way gangs break up their neighborhoods into unique territories is a lot like the way lions or honey bees break up space,” said lead author P. Jeffrey Brantingham, a professor of anthropology at UCLA.

Using police records, the researchers mapped the activities of 13 gangs in Boyle Heights, a neighborhood just east of Los Angeles. They found the most dangerous place to be wasn’t the heart of a gang’s territory, but near the borders:

To their surprise, most of the crimes fell on the borders that the model laid between gang territories. When crime locations did deviate from the borders, they did so in a configuration that was consistent with the model. For instance, the theory predicted that 58.8 percent of the crimes would occur within one-fifth of a mile of the border between two gangs — or just under two blocks — and 87.5 percent within two-fifths of a mile of the border — or just over three blocks. Overall, 99.8 percent of crimes could be expected to occur within one mile of the border, according to the theory.In fact, the team found that 58.2 percent occurred within two blocks of the border and 83.1 percent within just over three blocks of the border; in total, 97.7 percent of the crimes took place within one mile of the border between gangs.”You would think that we’re more complicated than other animals, so a model this simplistic shouldn’t work, but I was surprised that it fit as well as it did,” said co-author Martin B. Short, an assistant adjunct professor of mathematics at UCLA.

 Apparently Chicago could use this model, and fast: gang homicides are way up.