At almost 4,000 miles, it is the world's longest undefended border — separating the U.S. and Canada.
The issue here, say many analysts, isn't illegal immigration. It's security.
“The Canada-U.S. border,” says former Canadian Security Intelligence Service official David B. Harris, “does not look like it is a particular obstacle to possible terrorists trying to break across into the U.S. for dangerous purposes.”
In some places the border is so remote, it's hard to find. Just last year a hidden tunnel was discovered running between the two countries.
And in 1999, so-called "Millennium Bomber" Ahmed Ressam was arrested by U.S. officials as he was trying to cross the border with explosives. His target: Los Angeles International Airport.
“The concern is the Islamic extremists could use Canada as a place to locate and ultimately cross dozens of unmanned border locations,” says NBC News security analyst Roger Cressey,” and then disappear into the American population.”
The dilemma for security officials? Canada is the United States' largest trading partner. More than $1 billion in trade crosses the border every day. There are 70 million crossings each way, each year.
But security concerns will soon affect everyone.
Today, you simply need a birth certificate and a driver’s license to cross into the U.S. By 2008, everyone will require a passport.
“You don't want to threaten your economic security and vitality by trying to secure something,” says Scotty Greenwood of the Canadian American Business Council.
For 6o-plus years Windsor, Ontario's Tunnel Barbecue has fed travelers just a hundred feet from the border. Many of Tom Racovitis' customers are American. He now worries they will stay away.
“There seems to be this perception that around every corner there's a terrorist waiting,” he says. “We are really victims of fear-mongering.”
The Ambassador Bridge in Detroit is where much of that trade crosses to and from Canada. Security analysts say defending this vast border can never be done with troops — only shared cooperation and intelligence will keep both countries safe.