At least 90 per cent of Canada’s digital activity, from Facebook to Foursquare to basic email and beyond, is routed through exchange points in the United States, says Ronald Deibert, director of University of Toronto’s Citizen Lab.

The borderless nature of North America’s online architecture means the vast majority of Canadian metadata is filtered into the same U.S. National Security Agency surveillance systems exposed in blockbuster stories this week by The Guardian and The Washington Post.

“There is no border. The way telecommunication traffic is routed in North America, the fact of the matter is about 90 per cent of Canadian traffic — no one really knows the exact number — is routed through the United States,” Deibert told the Toronto Star.

“Internet exchange points are critical — this is where traffic is passed between companies — and we have only two Internet exchange points in Canada . . . As a consequence, even an email sent within the city of Toronto most likely would transit to Chicago before being routed back to Toronto.”

Along the way, your Canadian data is subsumed through “filters and checkpoints, shared with third parties, with law enforcement and of course intelligence agencies that operate in the shadows,” he said.

Those filters include the NSA’s previously undisclosed PRISM program, which operates with direct access to the systems of Google, Facebook, Apple and other U.S. Internet giants, according to top-secret documents obtained and published by The Guardian.