The growing trend of Canadian air travelers driving to U.S. airports is rooted in simple economics, the Conference Board of Canada reported Wednesday. The independent, not-for-profit research organization issued a subtle rebuke to all players in Canadian air travel, reminding them that money is the bottom line for many travelers. Researcher Vijay Gill said as many as 5 million Canadians avoid Canadian airports to save significant amounts. \"Cross-border air fare shopping is being driven by a \'perfect storm\' of factors that also includes differences in wages, aircraft prices and industry productivity as well as U.S. aviation policies,\" Gill wrote. \"But for air carriers flying from American airports, these add up to a 30 percent cost advantage.\" The board\'s report, \"Driven Away: Why More Canadians Are Choosing Cross-Border Airports,\" examined trends at international airports in Vancouver, Toronto and Montreal. The vast majority of Canada\'s 34 million people live within 100 miles of the U.S. border. The report said fees and taxes contribute to about 40 percent of the total airfare difference and suggested changes to Canadian policies alone could bring more than 2 million passengers a year back to Canadian airports.