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Mapping the Internet’s secret cables

The physical cables that form the Internet are one of our most vital forms of national infrastructure, up there with the highway system and the power grid. Yet despite their importance, almost no one knows where all those cables are. This makes it difficult to get an overall picture of what the Internet in the United States actually looks like.

By painstakingly pulling public records, however, Paul Barford has done it. Barford, a computer scientist at the University of Wisconsin, has created the first public map of the Internet as it exists today, making a hard-to-place form of infrastructure as tangible as the railroad network.


"What we found was nobody has this info," Barford says. "By piecing it together we were able to come up with something we think is compelling."

The information Barford is talking about is the location of the long-haul fiber optic cables that carry Internet data around the country, plus the hubs that transfer data between cables. Like other forms of infrastructure that have been laid by a patchwork of private firms (cell networks, phone lines, even railroads), a comprehensive map of the Internet is hard to come by. Companies like AT&T, Verizon, Windstream, and Level 3 have installed most of the equipment. They tend to keep their infrastructure investments quiet, so that their competitors don't immediately know what new services they plan to offer or what markets they're going after.

"If you went to Microsoft or Amazon and said tell me about your cloud services and what wires you have between them they'll say no, partly because it's hard for them and always changing and partly because it's proprietary," says Karen Sollins, a computer scientist at MIT. "This is all private, not like roads owned by the government. They get to do what they want, put them where they want, move things when they want. It's just proprietary, so finding it is really hard."


It is possible that the federal government maintains maps of Internet infrastructure. The information is closely held if it exists at all, which might provide a form of security, but also limits the number of people who can weigh-in on how to make the Internet better.

While companies may not be required to disclose their activities, they do leave clues behind, in the form of local permits that are required before any digging can begin. The permits often specify very exactly the routes that cables are going to take and together they bring the shape of the Internet into focus.

Barford's map, which he presented in August at the data communication conference SIGCOMM, contains crisscrossing lines and red dots. The lines are physical conduits for data, typically either 2-inch or 4-inch pieces of PVC pipe inside of which run 72 or 144 strands of fiber optic cable. The red dots are the hubs that transfer data between fiber optic lines, located in nondescript buildings on random streets in big cities across the country. As a matter of convenience, routes taken by the fiber optic cables tend to follow other kinds of infrastructure, like highways and railroads.

"Deployment along those rights-of-way is easier than if you're going through 50 farmers' cornfields," Barford says.

The map provides a satisfyingly concrete way to think about what happens every time you send an e-mail to Florida or query a server on in California. It's also a simple visual way to think about how to improve the Internet. Barford is interested in using the information he's compiled to increase performance and connectivity, build in redundancies that make Internet blackouts even less likely, and extend Internet infrastructure to underserved parts of the country — mainly large cable-less swaths west of the Mississippi.


Kevin Hartnett is a writer in South Carolina. He can be reached at