TORONTO -- True or false? Shortly before Sept. 11, 2001, several of the terrorists who would carry out the attacks that day slipped into the United States from Canada.
Canadian officials are vexed that 3 1/2 years later, they have not dispelled the groundless claim that Canada was a route for the Sept. 11 hijackers. Frank McKenna, the new ambassador to the United States, calls it an "urban myth" and has been trying to beat it down in television interviews and letters to the editor.
"It took on a life of its own, like a viral infection," McKenna said in a telephone interview from Washington.
This lingering headache for Canada underlines the enduring life of inaccuracies in the media and the sensitivity of Canadians to suggestions that their country's long and lightly guarded border is a threat to the United States.
"It's something that won't go away," Bill Graham, Canada's defense minister, said of the apocryphal claim in an interview Monday. "We're very resentful . . . because not one suspect had been in Canada. All had been in the U.S., training in the U.S., with valid U.S. visas."
The account was born in the first days after the attacks, when reporters and government investigators were scrambling to figure out how the conspirators had carried out the plot. Bernard Etzinger, a Canadian Embassy spokesman, says the "big bang" that started the legend can be traced to two Boston newspapers.
A Boston Globe story on Sept. 13 said investigators were "seeking evidence" that the hijackers came through Canada. The Boston Herald reported the same day that federal investigators believed "the terrorist suspects may have traveled . . . by boat" from Canada.
On Sept. 14, The Washington Post reported that an unnamed U.S. official had said two suspects "crossed the border from Canada with no known difficulty at a small border entry in Coburn Gore, Maine," and that others may have come through other Maine ports. On Sept. 16, that report was repeated by the New York Post, which also declared that "terrorists bent on wreaking havoc in the United States" had found Canada "the path of least resistance." On Sept. 19, the Christian Science Monitor referred to Canada as "a haven for terrorists."
"It was just one of those things where everybody says, 'We all knew that,' and it becomes irrefutable," Etzinger said.
In the weeks after the attacks, investigators established that all of the hijackers entered the United States from countries other than Canada, a finding that got the official stamp last summer with the release of the Sept. 11 commission report. But that has not stopped the story from spreading.
The Canadian Embassy in Washington keeps a chart of new reports of the rumor. The chart shows that at least three U.S. representatives and one senator have recently repeated the claim.
Sen. Hillary Rodham Clinton (D-N.Y.) was quoted in October as saying the terrorists had crossed into New York from Canada. Her office disputes the quotes, but they prompted a flurry of outrage and demands in Canada for an apology.
"It hurt Canadian feelings, particularly because we thought the Clintons were our pals," said Norman Hillmer, a professor at Carlton University in Ottawa and the author of a book on U.S.-Canadian relations.
In August, Rep. Ruben Hinojosa (D-Tex.) declared to a congressional committee -- and repeated in a press release -- that "as we all know, terrorists entered the U.S. from Canada on Sept. 11, 2001, using passports that the Canadians accepted as valid despite the fact that the documents were doctored."
The Canadian Embassy filed its now standard protest, and the congressman asked that the remarks be stricken from the committee record. He believed they were true from "some inferences," said his spokeswoman, Ciaran Clayton. "Those inferences were wrong."
"Once a story is out there, it gets picked up and repeated," Graham, the defense minister, said with a sigh. "People don't check to see if it's been contradicted."
Canadian officials concede that they are sensitive about the matter. "It vexes Canadians, because it's not just an untruth, but it's an untruth about one of the most . . . traumatic events of our lifetimes," McKenna said.
The sensitivity, they say, is heightened by fear that terrorists could infiltrate the United States from Canada. There is at least one known example of an attempt. In December 1999, border agents arrested an Algerian man, Ahmed Ressam, as he was trying to enter at Port Angeles, Wash., with homemade explosives in his rental car. He was later convicted of plotting to bomb the Los Angeles International Airport or some other airport in Southern California.
The 5,000-mile border stretches through unpoliced wilderness, and Canada's diverse population includes many people from countries racked by political turmoil. Officials worry that a terrorist attack traced to Canada would result in damaging restrictions on a border that more than 80 percent of Canada's exports cross.
Many Canadians reacted with irritation Tuesday to reports that they may have to show passports to enter the United States starting in 2007.