Internet scholars have been kicking around this idea since the early days of the World Wide Web, but it’s a particularly difficult one to test experimentally. Unlike studies that catalog how discrimination leads to generations of segregation in physical spaces—redlining in major American cities, for example—it’s not as easy to detect similar patterns on the web.

This year, Charlton McIlwain, a professor of media, culture, and communication at New York University, gave it a try. Applying theories that are usually used to study geographical segregation, McIlwain examined how people navigated through the internet to try and understand whether web traffic is segregated.

He approached the experiment with two questions. First, he wondered whether explicitly racial sites—sites that describe themselves in racial terms—link mostly to other racial sites, and non-racial sites link mostly to other non-racial sites. Second, he wanted to know how people moved between those sites, and whether or not they regularly hopped between those categories.

He began with the 56 “Top Black Sites” as chosen by Alexa, a web analytics company that ranks pages based on traffic and popularity. He used a software program that examined the network of links emanating from those sites, and ended up with more than 3,000 pages with nearly 16,000 links between them. (Those connections can take the form of hyperlinks in a news story, for example, or on a personal blog post.) Then, he used another analytics service to categorize those sites as “racial” or “non-racial” based on the way they described themselves for search engines.

When McIlwain looked at how the 3,000 sites he’d chosen were connected to one another, he found that non-racial and racial sites linked to each other in relatively equal measure: Neither type of site had a significant bias toward similar sites.

But divisions began to crop up when it came to how visitors actually navigated between the sites. McIlwain found that people who usually go to non-racial sites tend to visit other non-racial sites; similarly, visitors to racial sites preferred to click on other racial sites.

I asked McIlwain what it means that internet users self-segregate as they browse the web. He rephrased my question in terms of geography: “Why, when there’s a pathway to a different neighborhood, don’t I go there?” The answer, he thinks, has to do with the quiet ways that any space, virtual or physical, signals to visitors about itself.

“One has to look for the subtle, perhaps unintentional ways that sites are projecting a message,” he said. “‘This is an exclusionary place; this is a place that is not really meant for you. Yes, you have access—there’s a highway to get here—but we really don’t want you here, and there’s nothing for you here, anyway.’”

“I, as a person of color, may say, ‘Look, I know what is ‘for me,’ and those are a limited number of sites,’” McIlwain continued. “And that’s where I draw my boundaries.”