The busiest border crossing between the United States and Canada — the Ambassador Bridge in Detroit — is privately owned. It carries one-quarter of all trade between the two countries, worth about $100 billion a year. But government inspectors have limited access to the bridge, and it's not clear who is in charge of making sure it doesn't become a terrorist target.Like much infrastructure here in the US of A, this is just another target, albeit a big one and one that would have huge economic impact.
The bridge is owned by Manuel "Matty" Moroun, a reclusive billionaire distrusted by many people on both sides of the border. Moroun is now in a fierce battle with a government-run group over who gets to build the next crossing.
One of the big issues is security. Gregg Ward, who runs a nearby ferry for trucks that carry hazardous materials, is disturbed that uninspected trucks are allowed to park underneath the base of the Ambassador. They park there while truckers shop at the bridge's duty-free store on the American side. Trucks and cars can also fill up their tanks with discounted fuel. Ward says fuel trucks park under the bridge when they're filling up the underground storage tanks.
Anyway, check out Ms. Fessler's two part article; it includes background on the history of the bridge along with a discussion of the security concerns.