The theory: gentrification is taking over crime-ridden neighborhoods

The case for: For much of the 1980s, many inner-city areas were hubs of violent activity with barely any job opportunities. But in recent years, upwardly mobile immigrants and wealthier Americans have moved back into these neighborhoods, bringing jobs and economic prosperity with them.

The key, John Roman of the Urban Institute says, is these immigrants and gentrifiers didn’t push older residents out of inner-city neighborhoods. Instead, they all integrated into a more prosperous environment. This is important not just because it offers potential economic opportunities to longtime residents, but also because it didn’t push the poor into other neighborhoods, where economic hardship and violent crime may have taken root once again. (There’s some debate about whether this is true for all places witnessing the effects of gentrification, such as Washington, DC, and Prince George’s County in Maryland.)

Roman points to research that shows economically and racially segregated areas tend to have a lot more problems with crime. He cites the differences in crime in New York City, which has seen a lot of gentrification in recent years, and Chicago, which remains one of the most economically and racially segregated major cities in America. While New York City has seen homicides drop dramatically over the past few decades, Chicago’s homicide rate has seen a smaller decline.

The case against: While the research shows that gentrification isn’t anywhere near as harmful or displacing as some critics argue, it also indicates that gentrification is very rare. If gentrification is helping push down crime in inner-city neighborhoods, it’s not happening everywhere — or even in very many cities.

As Roman acknowledges, it’s hard to know, from a research perspective, how much of an impact gentrification has had on the crime rate. “It’s very difficult to test this all empirically,” he says.

The bottom line: Still unclear. Roman’s hypothesis certainly makes intuitive sense, and it’s backed by data from segregated and gentrified neighborhoods. But there’s very little research showing the direct impact of gentrification on crime, making it hard to gauge just how much of an effect is really there.