Where in the World Is … Everyone Who Travels?

There are plenty of things to love about travel—the thrill of new places, exposure to different cultures and cuisines, a chance to step outside the daily routine. But while jetting off to Europe or Mexico or Colorado is now as commonplace as a trip to the grocery store, we tend to label certain destinations as "desirable," and others not so much. Given that international travel can be so profitable—tourism accounts for more than 10 percent of the world’s gross domestic product—not to mention ubiquitous—the World Tourism Organization expects international traveler arrivals to reach 1.6 billion by 2020—it's worth asking: Where do people go on vacation, and why? Mathematician Joana Miguéns and physicist José Mendes of Portugal's Aveiro University set out to answer these questions, developing the first complete network of worldwide tourism. They constructed their model using WTO data from 2004, which included 763 million international tourist arrivals in 209 countries and territories. It depicts a tight series of links between countries, representing arrivals from one country to another, with each link becoming stronger to reflect a greater number of arrivals. (For a visual, see here.) A few of their findings are surprising, such as the fact that travel isn't always reciprocal: If say, Paraguay sends travelers to Romania, there's only a 25 percent chance that the Romanians will return the favor. Also, a huge number of countries giving each other no love: Up to 60 percent of all pairs of countries don’t exchange tourists at all. Less surprising is that the rule of popularity applies to travel: The more people who travel, the more likely they are to stick with already-popular destinations, as opposed to seeking out new vacation spots. Miguéns Mendes's model could be a major help to countries looking to market to other nations and maximize their tourism potential. Then again, everything may just hinge on oil prices.