FORT ERIE, ONT. -- Trucker Rob Shewan had been waiting yesterday for 13 hours to cross into the United States to deliver his trailer load of aluminum bars from Woodstock, Ont., to a wheel-making plant in Erie, Penn.

Stuck at this border crossing, he's fretting that the company receiving his cargo of metal might have to close if he doesn't get there soon.

"I believe that plant will have been shut down because they will not have been able to get material to process," Mr. Shewan said.

Mr. Shewan was among more than 1,000 big-rig operators caught in a massive traffic tie up at the Fort Erie border crossing yesterday as economic activity between Canada and the United States, the world's most active trading partners, slowed to a crawl.

Some of the worst delays were at Fort Erie, waiting to get on the Peace Bridge to the United States, but long waits were also experienced at Sarnia and Windsor.

The problems of the delayed truckers are some of the biggest economic collateral damage from the attack using hijacked planes to slam into the Pentagon and New York's World Trade Center.

U.S. customs inspectors have been ordered to conduct more extensive searches and identity checks, causing huge delays for businesses dependent on moving their goods across the border.

More than $1-billion in trade is exchanged between Canada and the United States every day. The vast majority moves in trucks, like Mr. Shewan's big 18-wheel tractor trailer. There are about 14 million truck trips across the Canada-U.S. border annually.

At one point early yesterday morning, Niagara Regional Police estimated that nearly 1,200 big rigs were waiting to cross at this Canadian border city on their way to destinations south of the border.

The delays are the worst veteran truckers have ever experienced, costing the economy an estimated $1-million an hour in lost productivity and other expenses, according to one industry estimate.

The story at Fort Erie was duplicated at other busy Canada-U.S. border crossings, according to industry officials.

"I'm hearing from our provincial associations in Quebec and B.C., in particular, but across the country, that they're facing delays," said David Bradley, chief executive officer of the Canadian Trucking Alliance, a trade association.