In fact, each city has a couple of distinct advantages that the other city lacks—Sudbury is at the centre of a larger economic sphere due to the city's, and Northeastern Ontario's, larger population, but Thunder Bay is advantaged by air, rail and shipping traffic due to its prime location along major continental transportation routes. The Thunder Bay International Airport is the third busiest airport in Ontario after Toronto Pearson International Airport and Ottawa Macdonald–Cartier International Airport, carrying some 600,000 passengers in 2004 with over 100 flights and four international flights daily. Sudbury's economy, in which the largest sectors of employment are government-related fields such as education and health care, is somewhat more diversified than Thunder Bay's, which is still based primarily on natural resources and manufacturing. Yet in the era of government cutbacks, Thunder Bay's economy has been less prone to recession and unemployment.