One roof at a time, Preston Rhea is casting an invisible net across Mount Pleasant. The 26-year-old field researcher for the Washington-based think tank New America Foundation has spent the past nine months nudging his neighborhood into a community wireless network. Routers, installed on six rooftops so far, open up people’s wireless connections to the public and allow any neighbor within a nine-block radius free access to the Internet.

Neighborhoods across the country are experimenting with these community-run “mesh networks,” including one that started and later stalled in the Bloomingdale area of Washington. Another grandiose plan that never made it off the drawing board aspired to cover the entire country in the wake of the SOPA/PIPA anti-piracy legislation debate.

For now, the Mount Pleasant network is seeing a slow but steady growth. “It’s the Internet equivalent of neighbors sharing a cup of sugar,” Rhea said in a phone interview.

The premise is simple: People unlock their networks and allow others, who might not be able to afford it, to access the Internet.

As it is now, look for a wireless network in the Mount Pleasant neighborhood and you’ll find 20 of them all locked away, allowing only the owners the ability to log onto the Internet. This is despite the fact that, Rhea says, people pay for the full capacity of broadband Internet but rarely use all of it. That extra broadband can be given away with little interference to their own usage.

In D.C.’s Mount Pleasant, one man who set up a ‘mesh network’ hopes wireless access for the whole neighborhood isn’t a failed exercise. (The Washington Post)

In a mesh network, someone volunteers to be a host router, and he opens up a portion of his monthly allotted broadband to the neighborhood. Others host routers that allow the network to reach farther than most wireless networks. People along Monroe and Lamont streets now can log onto the “MTPCWN” network. Rhea said they shouldn’t expect to always be able to stream videos, but they should be able to send e-mail and check the news.

While this all sounds like Mister Rogers’s Neighborhood Gone Digital, there are those who worry about security, both public and private. Rhea says the potential danger is no greater than what you encounter logging onto a WiFi network at a coffee shop. He says he’s working to create better protection and to educate network users about ways they can protect themselves.

The other concern is broader and more difficult to pin down. Washington’s new chief technology officer, Rob Mancini, told the Washington City Paper that his office would be watching mesh networks closely for potential threats to national security. Because those networks often do not have the capability to trace who is using the systems, they have the potential to attract terrorists, Mancini said.

Supporters of mesh networks dismiss these fears. Rhea compares it to the 1960s battle against AT&T, which cited security concerns in its attempt to block new technology that could be attached to the telecommunication system.

The real problem, Rhea says, is not the technology — “it’s the human element.” To make the network function, volunteers need to be willing to open up their rooftops and networks to strangers. The infrastructure then relies on volunteers for maintenance, not paid staff on hotlines.

To Rhea, though, the work is worth it. Six months after opening up the network, Rhea posted an e-mail he received on a mesh network message board: A woman had written to thank him for the free Internet access. She had used it as she sat by her dying mother’s bedside at a neighborhood nursing home.

“I can stay in touch with friends and relatives and either get some work done during quiet times or, frankly, distract myself, also a gift. . . . You probably don’t know who you’re helping half the time, so here’s one story.”